General Science for Railway 2023 PDF

 INDEX UNITS AND MEASURMENTS- 1 TO 4 ELECTRIC CURRENT- 5 TO 18 LIGHT- 18 TO 34 SOUND- 34 TO 43 FORCE AND MOTION- 44 TO 51 WORK AND ENERGY- 51 TO 56 CELL- 56 TO 65 DIGESTIVE SYSTEM- 65 TO 73 CIRCULATORY SYSTEM- 83 TO 86 REPRODUCTIVE SYSTEM- 86 TO 94 VITAMINS- 94 TO 96 PERIODIC TABL...

 INDEX UNITS AND MEASURMENTS- 1 TO 4 ELECTRIC CURRENT- 5 TO 18 LIGHT- 18 TO 34 SOUND- 34 TO 43 FORCE AND MOTION- 44 TO 51 WORK AND ENERGY- 51 TO 56 CELL- 56 TO 65 DIGESTIVE SYSTEM- 65 TO 73 CIRCULATORY SYSTEM- 83 TO 86 REPRODUCTIVE SYSTEM- 86 TO 94 VITAMINS- 94 TO 96 PERIODIC TABLE- 96 TO 105 METALS & NON-METALS- 105 TO 119 ACID, BASE & SALTS- 119 TO 126 ATOMS & MOLECULES- 126 TO 136 PREVIOUS YEAR- 137 TO 154 PRACTICE SETS- 155 TO 221 FORMULAS & NUMERICALS- 222 TO 248  MEASURMENTS & UNITS Definition of physics: The branch of science concerned with the nature and properties of matter and energy. Measurement: In Number: 1) Octal 2) Decimal 3) Hexadecimal In Unit: The word unit as used in physics binary refers to the standard measure of a quantity. Units: Unit are mainly two types :- Basic unit: Total basic unit are 7 ⇒ 6-physics + 1- chemistry Derived unit: ∞ (infinity) The SI base units are the standard units of measurement defined by the International System of Units(SI) for the seven base quantities. I. system starts in 1961 (in jenewa) In S.I. system dimensional formula is [M L T] where, M for mass, L for length, T for time. S.I. System: Sl. No. Name of the Quantity SI Unit SI Unit Symbol 1. Length (l) Meter m 2. Mass (M) Kilogram kg 3. Time (T) Second s 4. Electric current (I) Ampere A 5. Thermodynamic temperature (Θ) Kelvin K 6. Luminous intensity (J) (light) candela cd 7 Amount of substance (N) Mole mol 1|P ag e This 7th unit is Chemistry unit. Physical Quantities: – These are those quantities which can be measured accurately. These are mainly two types: Scalar quantity: The physical quantity with magnitude only, no direction. E.g. Mass, Speed etc. Vector quantity: A vector is a quantity that has both a magnitude and a direction. For e.g.- force, velocity, acceleration, displacement, and momentum etc. Some Important Measurement Units of Physics: 1) Light year:– It is unit of distance through which distance of celestial objects can be measured. Distance travelled by light in a year is called One-Light-year. Speed of light= 3 x 108 m/sec Distance travelled by light in a year = 9.46 x 1012 KM or 9.46 x 1015 meters. 2) Parsec: – It is largest unit of distance by which distance of celestial (astronomical) object can be measured. It is 3.25 times more than the light year. 1 parsec = 2.49 x 1013 k.m. or 2.49 x 1016 meters. 3) Astronomical unit: – It is also the unit of distance by which the distance of celestial (astronomical) object can be measured. 2|P ag e It is average distance between Sun and Earth. 1-astronomical unit = 1.5 x 108 Km or 1.5 x 1011 meters. 4) Fermi unit: – It is the smallest unit of distance through which atomic radius can be measured. It is Atomic distance between molecules. 1-Fermi = 10-15 meter 5) Nautical mile: – This is the unit of distance through which distance in “ocean” as well as “in air” can be measure. 1 nautical mile = 1852 meter 6) Naute: – It is a unit by which the speed of ship can be measured. naute = 1852 meter/hours 7) Fathem: – It is unit by which “Depth of ocean” can be measured. Fathem = 6 feet 8) Cusec: – It is unit through which “flow of liquid” can be determine. 1 cusec = feet3 /sec & 3|P ag e 1 cusec = 28 litre 9) Poise: – It is a unit through which viscosity of liquid can be measured. Facts: “clouds” floths in the sky due to less viscosity and low density. 10) Pascal: – It is unit through which “pressure of gas” can be measured. 1 pascal = 1 N/m2 11) Diopter: – It is unit through which “power of lens” can be measure. 12) Richter scale: – Unit through which intensity of earth quack can be measured 13) PH- Scale: – Through which “strength of acid and base” can be measured. 14) Curine/Rutherford/Brequell: – These are units through which “Intensity of Radio activity” can be measured. 15) Decibel:- It is unit through which Intensity of the sound can be measured. 16) Aung strung (Aº):- It is unit through which cellular component like membrane etc. can be measured. 1 A º= 10-10 meter 4|P ag e  Electric Current Electric current is expressed by the amount of charge flowing through a particular area in unit time. It is the rate of flow of electric charges. If a net charge Q, flows across any cross-section of a conductor in time t, then the current I, through the cross-section is- I = Q/t The SI unit of electric charge is the coulomb (C), which is equivalent to the charge contained in nearly: 6 x 10¹⁸ electrons The electric current is expressed by a unit called ampere (A). One ampere is constituted by the flow of one coulomb of charge per second, that is, 1A = 1C/1s. ELECTRIC POTENTIAL AND POTENTIAL DIFFERENCE The electric potential difference between two points in an electric circuit carrying some current is the work done to move a unit charge from one point to the other Potential difference (V) between two points = Work done (W)/Charge (Q) V = W/Q The SI unit of electric potential difference is volt (V), named after Alessandro Volta (1745–1827), an Italian physicist. One volt is the potential difference between two points in a current-carrying conductor when 1 joule of work is done to move a charge of 1 coulomb from one point to the other. 5|P ag e The potential difference is measured by means of an instrument called the voltmeter. The voltmeter is always connected in parallel across the points between which the potential difference is to be measured. ELECTRIC CURRENTS IN CONDUCTORS In other materials, notably metals, some of the electrons are practically free to move within the bulk material. These materials, generally called conductors, develop electric currents in them when an electric field is applied. In solid conductors: When no electric field is present- The number of electrons traveling in any direction will be equal to the number of electrons traveling in the opposite direction. So, there will be no net electric current. If an electric field is applied- An electric field will be created and is directed from the positive towards the negative charge. They will thus move to neutralize the charges. The electrons, as long as they are moving, will constitute an electric current. OHM’S LAW Imagine a conductor through which current I is flowing and let V be the potential difference between the ends of the conductor.Ohm’s law states that: V∝I or, V = R I; where the constant of proportionality R is called the resistance of the conductor. The SI units of resistance is ohm, and is denoted by the symbol Ω. 6|P ag e The resistance of the conductor depends- on its length, on its area of cross-section, and on the nature of its material. LIMITATIONS OF OHM’S LAW V ceases to be proportional to I The relation between V and I depends on the sign of V. In other words, if I is the current for a certain V, then reversing the direction of V keeping its magnitude fixed, does not produce a current of the same magnitude as I in the opposite direction The relation between V and I is not unique, i.e., there is more than one value of V for the same current I A material exhibiting such behavior is GaAs. RESISTIVITY The resistance of a uniform metallic conductor is directly proportional to its length (l) and inversely proportional to the area of cross-section (A). That is, R ∝ l and R ∝ 1/A Combining both, we get R ∝ l/A or, R = ρl/A where ρ (rho) is a constant of proportionality and is called the electrical resistivity of the material of the conductor. The SI unit of resistivity is Ω m. It is a characteristic property of the material. 7|P ag e RESISTIVITY OF VARIOUS MATERIALS The resistivity of a material is found to be dependent on the temperature. The resistivity of an alloy is generally higher than that of its constituent metals. Alloys do not oxidize (burn) readily at high temperatures. For this reason, they are commonly used in electrical heating devices, like electric iron, toasters, etc. Tungsten is used almost exclusively for filaments of electric bulbs, whereas copper and aluminum are generally used for electrical transmission lines. Some materials like Nichrome (which is an alloy of nickel, iron, and chromium) exhibit a very weak dependence of resistivity with temperature. Unlike metals, the resistivities of semiconductors decrease with increasing temperatures. TWO MAJOR TYPES OF RESISTORS: Wire bound resistors: They are made by winding the wires of an alloy, viz., manganin, constantan, nichrome or similar ones. The choice of these materials is dictated mostly by the fact that their resistivities are relatively insensitive to temperature. These resistances are typically in the range of a fraction of an ohm to a few hundred ohms. Carbon Resistors: Resistors in the higher range are made mostly from carbon. Carbon resistors are compact, inexpensive and thus find extensive use in electronic circuits. Carbon resistors are small in size and hence their values are given using a colour code. RELATION OF CURRENT AND DRIFT VELOCITY When an electric field is applied, inside the conductor due to electric force the path of an electron, in general, becomes curved (parabolic) instead of straight lines, and electrons drift opposite to the field figure (B). Due to this drift, the random motion of electrons gets modified and there is a net transfer of electrons across a cross-section resulting in current. 8|P ag e Drift velocity is the average uniform velocity acquired by free electrons inside a metal by the application of an electric field which is responsible for current through it. ELECTRICAL ENERGY AND POWER The rate at which electric energy is dissipated or consumed in an electric circuit is termed as electric power. The power P is given by P = VI Or P = I²R = V²/R The SI unit of electric power is the watt (W). It is the power consumed by a device that carries 1 A of current when operated at a potential difference of 1 V. Thus, 1 W = 1 volt × 1 ampere = 1 V A The commercial unit of electric energy is kilowatt-hour (kW h), commonly known as ‘unit’ CELLS IN SERIES AND IN PARALLEL Cell: A cell is a device that generates electricity by using chemical energy. A cell has two electrodes, called the positive (P) and the negative (N), immersed in an electrolytic solution where the electrodes exchange charges with the electrolyte. Note:- Current flows from cathode to anode through an external circuit. Current flows from anode to cathode through the electrolyte. EMF (Electromotive force): It is defined as the potential difference between electrodes when there is no current in the cell.Emf of the cell initiates the flow of current in the cell. 9|P ag e Internal Resistance: It is the resistance offered by the electrolyte and electrodes when the current flows. It is denoted by ‘r’ Cells in Series When multiple cells are arranged in such a way that the positive terminal of one cell is connected to the negative terminal of the other cell and so on, it is known to be in series combination. For two cells of emf’s E1 and E2 connected in series with r1, r2 as their internal resistances, the formula is given as: E equivalent = E1 + E2 r equivalent = r1 + r2 The rule for cells arranged in series combination: The equivalent emf of a series combination of n cells is just the sum of their individual emf’s, and The equivalent internal resistance of a series combination of n cells is just the sum of their internal resistances. Cells in Parallel When cells are arranged in such a way that the positive terminals of all the cells are connected together and all the negative terminals are connected together, it is known to be in parallel combination. For two cells of emf’s E1 and E2 connected in parallel with r1, r2 as their internal resistances, the formula is given as: 1/r equivalent = 1/r₁ + 1/r₂ E equivalent/ r eq = E₁/r₁ + E₂/r₂ Important Note:- Cells are arranged in series to increase the voltage. Cells are increased in parallel to increase the current. 10 | P a g e POTENTIOMETER It is basically a long piece of uniform wire, sometimes a few meters in length across which a standard cell is connected. A current I flows through the wire which can be varied by a variable resistance (rheostat, R) in the circuit. Since the wire is uniform, the potential difference between A and any point at a distance l from A is E(l) = ⌽l where ⌽ is the potential drop per unit length.An application of the potentiometer is to compare the emf of two cells of emf ε1 and ε2 which is given by the equation: E1/E2 = l1/l2 The potentiometer has the advantage that it draws no current from the voltage source being measured. Potentiometer is also used to measure the internal resistance of a cell. Conductor: A substance that allows the passage of electric charges through it easily is called a conductor. A conductor offers very low resistance to the flow of current. For example copper, silver, aluminum etc. Insulator A substance that has infinitely high resistance does not allow electric current to flow through it. It is called an insulator. For example rubber, glass, plastic, Ebonite etc. Coulomb’s Law: The mutual electrostatic force between two point charges q₁ and q₂ is proportional to the product q₁ q₂ and inversely proportional to the square of the distance r₂₁ separating them. 11 | P a g e QUICK REVISION 1. Electricity is the set of physical phenomena associated with the presence and flow of electric charge. 2. Electrons have a negative charge. 3. An Electric (force) field surrounds any charged object – it spreads out – weakens with distance. 4. The charge is measured in Coulombs. 5. 1 Coulomb =1 amp per second. 6. In a good conductor, the valence electrons can be easily forced to move from one atom to the next. 7. A conductor is a material that has a large number of free electrons that continually jump to other atoms. 8. Good electrical conductors are copper and aluminum. Gold, silver, and platinum are also good conductors but are very expensive. 9. An insulator is a material that has only a few free electrons. In insulators, the electrons are tightly bound by the nucleus. 10. Good electrical insulators are Rubber, Porcelain, Glass, and Dry Wood. 11. Current (I) is the movement of charge through a conductor. Electrons carry the charge. 12. Unit of measurement current in Amperes (A). 13. The fundamental electric quantity is Charge. 14. Current is the rate of flow of negatively-charged particles, called electrons, through a predetermined cross-sectional area in a conductor. 12 | P a g e 15. Resistance – The ability to resist current leakage through and over the surface of the material. 16. The resistance, expressed in ohms ( named after George ohm) 17. Resistance depends on Resistivity, Length, Cross-sectional area, and Temperature. 18. An ammeter is used to measure the amount of current. 19. A voltmeter is used to measure the potential difference between two points. 20. An instrument used to measure resistance is Ohm meter. 21. A capacitor is an energy storage element. 22. It can store electrical voltage for periods of time. 23. A Capacitor consists of two conducting metal plates with an insulating sheet of material in between. 24. When a capacitor has a difference in voltage across its plate, it is said to be charged. 25. Unit of capacitance is Farad 26. Inductance (L) is the property of an electrical circuit that opposes the change in current. 27. An inductor is a passive energy storage element that stores energy in the form of a magnetic field. 28. The henry (symbolized H) is the Standard International ( SI ) unit of inductance. 29. Ohm’s law states that an electric current is proportional to voltage and inversely proportional to resistance. 30. When current flows through a conductor, heat energy is generated in the conductor. 13 | P a g e 31. The heating effect of an electric current depends on resistance, amount of current, and time for which current flows. 32. The heating effect of current is used in Iron box, electric water heater, etc. 33. The magnetic field carries the invisible force of magnetism 34. Wherever an electric current exists, a magnetic field also exists. 35. Whenever current flows through a conductor, a magnetic field is created around the conductor. 36. The rule for remembering the direction of the magnetic field around a conductor is called the right–hand clasp 37. If a person grasps a conductor in one’s right hand with the thumb pointing in the direction of the current, the fingers will circle the conductor in the direction of the magnetic field. 38. An electromagnet is a type of magnet in which the magnetic field is produced by an electric current. 39. In electromagnets, the magnetic field disappears when the current is turned off. 40. Electromagnets are used in motors, generators, relays, loudspeakers, hard disks, MRI machines, scientific instruments, and magnetic separation equipment. 41. Electromagnetic Induction creates a voltage or current in a conductor when a magnetic field change. 42. In a transformer, alternating current in one winding induces a changing magnetic field in the transformer core 43. Transformer work on the principle of Electromagnetic induction. 44. In Generator magnetic field of the rotor induces a voltage in the stator windings. 14 | P a g e 45. Electromagnetic induction was first discovered by Michael Faraday. 46. Dynamo works on the basis of Faraday’s law. 47. Whenever a magnetic field is moved past a conductor a voltage is induced in the conductor. 48. Farad determined that a capacitor has a value of one farad of capacitance if one volt of the potential difference applied across its plates moved one coulomb of electrons from one plate to the other. 49. Electric bell functions by means of an electromagnet. 50. Lenz’s law states that the polarity of the induced emf is such that it tends to produce a current which opposes the change in magnetic flux that produces it. 51. When the current in a coil changes, it induces a back emf in the same coil. 52. The magnitude of the induced emf in a circuit is equal to the time rate of change of magnetic flux through the circuit. 53. The induced emf can be increased by increasing the number of turns N of a closed coil. 54. By accelerating magnet inside a coil, current in it increases. 55. A total number of magnetic field lines passing through an area is called magnetic flux. 56. The magnitude of induced e.m.f is proportional to the rate of change of magnetic flux linkage. 57. In a transformer, the core is made up of soft iron in order to pass maximum magnetic flux. 58. Currents that flow in circles inside a disc are known as eddy currents. 59. When the field is parallel to the plane of area, the magnetic flux through the coil is zero. 15 | P a g e 60. An open coil has infinite resistance and zero inductance. 61. In the case of inductance, the current is proportional to the magnetic field. 62. For a purely inductive circuit, the Actual power of the circuit is zero. 63. Lenz’s law is a consequence of the law of conservation of energy. 64. The coefficient of coupling between two air core coils depends on mutual inductance and self-inductance of two coils. 65. A crack in the magnetic path of an inductor will result in reduced inductance. 66. The inductance will oppose the change in circuit current. 67. Weber is the unit of magnetic flux. 68. C cannot be used for magnetizing and electroplating. 69. Inductors act as a short circuit for DC. 70. Long-distance transmission is easy for AC. 71. When the motor is at its maximum speed then back emf will be maximum 72. The reluctance in a magnetic material is a property by virtue of which it opposes the creation of Magnetic flux. 73. Coulomb’s First Law states that unlike poles attract each other and like poles repel each other. 74. The electrical entity inductance can be compared to the mechanical entity inertia. 75. In electroplating, the solution must be of salt of the metal to electroplate with. 76. Types of electrodes used during electrolysis affect the products of electrolysis. 77. A battery converts chemical energy into electrical energy. 78. When an electric current is passed through a bulb, the bulb gives light because of the heating effect of current. 16 | P a g e 79. The process of producing chemical decomposition of a compound by passing electricity through the compound is called electrolysis 80. The filament used in an electric heater is of high resistance. 81. Mica is a bad conductor of electricity but a good conductor of heat. 82. Conversion of temperature into electric voltage is done with thermistor 83. Wire wound variable resistance is known as a rheostat 84. The potential difference between ends of conductor maintained by the battery is 85. SI unit of conductivity of material isΩ-1m-1. 86. Ohmic devices are devices that consequently obey Ohm’s law. 87. Filament bulbs are best examples of the non-ohmic devices 88. Reciprocal of resistance is called conductance 89. A living creature that turns itself into living battery is eel 90. The characteristic specific resistance of a wire is its resistivity 91. Sunlight is directly converted into electrical energy by using solar cells. 92. To pass current through ammeter it should be connected in series in the circuit. 93. Inside a hollow conducting sphere electric field is zero. 94. To obtain a high value of capacitance, the permittivity of the dielectric medium should be high. 95. 1 F is theoretically equal to the ratio of 1 C to 1 V. 96. The bulb in street lighting are connected in parallel. 97. The third pin of a 3-pin plug is thicker and longer for protection purposes. 98. Our household apparatus are connected in parallel 17 | P a g e 99. The internal resistance of an ideal voltage source is zero 100. The internal resistance of an ideal current source is infinity LIGHT Light: Light or visible light is a transverse, electromagnetic wave that can be seen by the human eyes. Electromagnetic waves: – Electromagnetic waves have not need of any medium to propagate. Light can travel through a vacuum. So, light is also not required any medium to propagate. It can be travelled in vacuum also. Important Facts of light:- The speed of light in a vacuum is a universal constant in all reference frames. The speed of light in a vacuum is fixed at 299,792,458 m/s by the current definition of the meter. The speed of light in a medium is always slower the speed of light in a vacuum. The speed of light depends upon the medium through which it travels. The speed of anything with mass is always less than the speed of light in a vacuum. Other Characteristics:- The amplitude of a light wave is related to its intensity. Intensity is the absolute measure of a light wave’s power density. 18 | P a g e Brightness is the relative intensity as perceived by the average human eye. The frequency of a light wave is related to its color. The wavelength of a light wave is inversely proportional to its frequency. Light ranges in wavelength from 400 nm on the violet end to 700 nm on the red end of the visible spectrum. Electromagnetic Wave Spectrum: – Electromagnetic radiation have a wide range of wavelengths, from gamma rays to radio waves measured in meters. Band of visible light comes, from about 700 nanometers (nm) for red light to about 400 nm for violet light. Visible light: White light is the mixture of all 7 color of visible light. There are three fundamental (primary) color: BLUE, GREEN, RED. Red color of light use in dangerous sign because: Due to their higher wavelength and less scattering. It can be seen from far distance. Electromagnetic Wave uses:- 19 | P a g e Category of Radiation Uses Gamma rays Give information on nuclear structure, used to kill the bacteria in marshmallows and to sterilize medical equipment X-rays used to image bone structures Ultraviolet light (UV rays) Preserve food, sterilizing the surgical treatments, finger prints, bees can see into the ultraviolet light. Visible Light It used by humans to see objects Infrared Night vision, Heat sensors, Laser metal cutting Microwave Microwave ovens, Radar, Telecommunication Radio Waves Radio, Television Broadcasts. Geiger Muller Counter (GM counter): – This device used for the detection and measurement of all types of radiation alpha, beta and gamma radiation Discovery of electromagnetic waves: U.V. waves discovered by: Johann Ritter X – Rays discovered by: Wilhelm Roentgen Cosmic or radioactive rays discovered by: Antoine Henri Becquerel Visible light discovered by: Newton Wireless waves discovered by: Guglielmo Marconi Scattering of light: Scattering of light is the phenomenon in which light rays get deviated from its straight path on striking an obstacle like dust or gas molecules, water vapors etc. Important Fact of scattering of light: 20 | P a g e Violet color light has maximum scattering. In foggy weather, yellow color of light use in automobiles because it’s least scattering. Sky appears blue due to scattering of light, or due to presence of dust and moisture in atmosphere. Low wavelength of light, scatter more. At the surface of moon sky appears black because there is no atmosphere, hence scattering of light does not occur. Light and Its Facts Phenomenon of light: – Absorption Reflection Refraction 1. Light Absorption: Light absorption is a process by which light is absorbed and converted into energy. Absorption depends on the electromagnetic frequency of the light and object’s nature of atoms. The absorption of light is therefore directly proportional to the frequency. If they are complementary, light is absorbed. Important Facts of absorption: If an object absorbed all the color of the light, they appear “BLACK”. If an object reflect all the color of the light, it appear white. 21 | P a g e When we see any color of any object, it means seen color is reflected color and all other 6 color absorbed. 2. Reflection: The process through which light rays falling on the surface on an object are sent back or bounces back the light is called reflection of light. If an object reflect all the color of the light, it appear white. 3. Refraction: Refraction is the bending of a wave when it enters a medium where its speed is different. The refraction of light when it passes from a fast medium to a slow medium bends the light ray toward the normal to the boundary between the two media. The amount of bending depends on the index of refraction. “The index of refraction” is defined as the speed of light in vacuum divided by the speed of light in the medium. (Index of refraction) N = c/v where, c is velocity of light in vacuum and v is the velocity of light in medium. Important Facts of Refraction: The depth of swimming pull appears less than its original depth, due to refraction of light. A rod emerged in water appears bend due to refraction of light. Twinkling of the stars occurs due to refraction of light. A glass rod emerged in water, it goes disappear because of refractive index of water and glass are same. 22 | P a g e At the time of sun rise and sun set, sun appears large and oval size due to refraction of light. Some important points: Incident ray: The ray of light falling on the surface of a mirror is called incident ray. Normal: A line perpendicular or at the right angle to the mirror surface at the point of incidence is called normal. Angle of incidence: The angle made by the incident ray with the normal is called angle of incidence. Total Internal Reflection: – Total internal reflection occurs when the light rays travel from a more optically denser medium to a less optically denser medium. Conditions of Total Internal Reflection: The light ray moves from a denser medium to less dense medium. The angle of incidence must be greater than the critical angle. FACTS of Total Internal Reflection: Diamond shine too much due to total internal reflection of light. Mirage form due to total internal reflection of light. Working of optical fiber based upon total internal reflection of light, which is widely use in communication and endoscopy surgery. 23 | P a g e Diffraction of Light:- Light bends when it passes around an edge or through a slit that is physically the approximate size of, or even smaller than that light’s wavelength. This bending is called diffraction. Important Facts of diffraction of light: Before sun rise and after sun set, light present in sky due to diffraction of light. CD appears like rainbow colors due to diffraction reflection of light simultaneously. Shop bubble appears rainbow colorist due to diffraction of light. If a kerosene oil pore in water, then layer of water look like rainbow colors due to diffraction and reflection of light. Dispersion of Light: – When white light is passed through a glass prism it splits into its spectrum of colors (in order violet, indigo, blue, green, yellow, orange and red) and this 24 | P a g e process of white light splitting into its constituent colors is termed a dispersion. Important Facts of dispersion: Formation of rainbow occur due to dispersion of light. Prizm also showing different color by the dispersion of light. Maximum dispersion of light in violet color. Minimum dispersion of light in yellow color. Some Other Important points About Light: At the time of eclipse, rectilinear propagation of light takes place. Due to rectilinear propagation of light shadow forms. At the time of formation of rainbow, sun must behind the rainbow. At the time of noon 12, rainbow can’t be seen. At a time maximum 2 rainbow can see. SPHERICAL MIRRORS The reflecting surface of a spherical mirror may be curved inwards or outwards. For spherical mirrors of small apertures, the radius of curvature is found to be equal to twice the focal length i.e. R = 2f. This implies that the principal focus of a spherical mirror lies midway between the pole and centre of curvature. 25 | P a g e 1.Concave mirror A spherical mirror, whose reflecting surface is curved inwards, that is, faces towards the centre of the sphere, is called a concave mirror. Image formation by a concave mirror Uses of concave mirrors Used in torches, search-lights and vehicles headlights to get powerful parallel beams of light. As shaving mirrors to see a larger image of the face. The dentists use concave mirrors to see large images of the teeth of patients. Large concave mirrors are used to concentrate sunlight to produce heat in solar furnaces. 2.Convex mirror A spherical mirror whose reflecting surface is curved outwards, is called a convex mirror. 26 | P a g e Image formation by a convex mirror Uses of a convex mirror Commonly used as rear-view (wing) mirrors in vehicles. These mirrors are fitted on the sides of the vehicle, enabling the driver to see traffic behind him/her to facilitate safe driving. It enables the driver to view much larger area than would be possible with a plane mirror. In big showrooms and departmental stores, convex mirrors are used to have a view on the customers entering in as well as going out. Important terms- Ray of Light : A line drawn in the direction of propagation of light is called a ray of light. Beam of Light : A group of rays of light emitted by a source of light is called a beam of light. A light beam is of three types. Real Image : It is a kind of image which is formed by actual intersection of light rays after reflection. Virtual Image : It is a kind of image which is formed by producing the reflected rays backward after reflection. Pole: The centre of the reflecting surface of a spherical mirror is a point called the pole. It lies on the surface of the mirror. 27 | P a g e Centre of curvature: The reflecting surface of a spherical mirror forms a part of a sphere. This sphere has a centre. This point is called the centre of curvature of the spherical mirror. Radius of curvature: The radius of the sphere of which the reflecting surface of a spherical mirror forms a part, is called the radius of curvature of the mirror. Principal axis: A straight line passes through the pole and the centre of curvature of a spherical mirror. This line is called the principal axis. Principal Focus: When rays from infinity come in parallel to the optical axis of a spherical mirror, they are bent so that they either converge and intersect in at a point, or they seem to diverge from a point. The point of convergence or divergence is called the focus. It is denoted by letter F. Focal length: The distance between the pole and the principal focus of a spherical mirror is called the focal length. It is represented by the letter f. Aperture: The diameter of the reflecting surface of spherical mirror is called its aperture. Magnification: Magnification produced by a spherical mirror gives the relative extent to which the image of an object is magnified with respect to the object size. If h is the height of the object and h′ is the height of the image, then the magnification m produced by a spherical mirror is given by: The magnification m is also related to the object distance (u) and image distance (v): 28 | P a g e MIRROR FORMULA In a spherical mirror, the distance of the object from its pole is called the object distance (u). The distance of the image from the pole of the mirror is called the image distance (v). The distance of the principal focus from the pole is called the focal length (f). There is a relationship between these three quantities given by the mirror formula which is expressed as- Sign Convention for Reflection by Spherical Mirrors While dealing with the reflection of light by spherical mirrors, we shall follow a set of sign conventions called the New Cartesian Sign Convention. In this convention, the pole (P) of the mirror is taken as the origin. The principal axis of the mirror is taken as the x-axis (X’X) of the coordinate system. The conventions are as follows – 29 | P a g e (i)The object is always placed to the left of the mirror. This implies that the light from the object falls on the mirror from the left-hand side. (ii) All distances parallel to the principal axis are measured from the pole of the mirror. (iii)All the distances measured to the right of the origin (along + x-axis) are taken as positive while those measured to the left of the origin (along – x- axis) are taken as negative. (iv)Distances measured perpendicular to and above the principal axis (along + y-axis) are taken as positive. (v)Distances measured perpendicular to and below the principal axis (along –y-axis) are taken as negative. QUICK REVISION 1. Light is in the form of an electromagnetic wave 2. The visible light has wavelengths stretches between 400–700 nanometres. 3. The primary source of light is sun. 4. Optics is a branch of physics that deals with the properties and behaviour of light, along with its interactions with the matter. 5. Light exhibits various properties which are Reflection, Refraction, Total internal reflection, Dispersion. 6. Light speed is 3 x 108 m/s which is the form of energy. 7. Light is a transverse wave. 8. When light falls on the surface of an object it can either be- Absorbed, Transmitted, Reflected 30 | P a g e 9. If an object absorbs all the light falling on it, then it will appear perfectly black for example a blackboard. 10. An object is said to transmit light if it allows light to pass through itself and such objects are transparent. 11. If an object sends back light rays falling on its surface then it is said to have reflected the light. 12. When a ray of light falls on a boundary separating two media comes back into the same media, then this phenomenon is called the reflection of light. 13. The angle of incidence is equal to the angle of reflection. 14. The incident ray, the reflected ray and the normal to the mirror at the point of incidence all lie in the same plane. 15. To see his full image in a plane mirror, a person required a mirror of at least half of his height 16. Laws of reflection are applicable to all types of reflecting surfaces including spherical surfaces. 17. The reflecting surface of a spherical mirror may be curved inwards or outwards. 18. A spherical mirror, whose reflecting surface is curved inwards, that is, faces towards the centre of the sphere, is called a concave mirror. 19. A spherical mirror whose reflecting surface is curved outwards, is called a convex mirror. 20. The reflecting surface of a spherical mirror forms a part of a sphere which has a centre- That point is called the centre of curvature of the spherical mirror. 21. The centre of curvature is not a part of the mirror. It lies outside its reflecting surface. 22. The centre of curvature of a concave mirror lies in front of it. 31 | P a g e 23. The centre of curvature of a convex mirror lies behind the mirror. 24. The phenomenon of deviation of light rays from its path when it travels from one transparent medium to another medium is called refraction of light. 25. The cause of refraction is due to the different speed of light in the different medium. 26. When a ray of light enters from one medium to another medium, its frequency and phase do not change, but wavelength and velocity change. 27. Due to refraction from Earth’s atmosphere, the stars appear to twinkle. 28. The incident ray, the refracted ray and the normal at the point of incidence all three lie in the same plane in refraction of light. 29. The ratio of sine angle of incidence to the sine angle of refraction remains constant for a pair of media. = constant = , this law is known as Snell’s law or law of refraction of light. 30. When light travels through a denser medium towards a rarer medium it deviates away from the normal, therefore a pond appears shallower. 31. A coin appears at lesser depth in water. 32. The angle of incidence in a denser medium for which the angle of refraction in rarer medium becomes 90°, is called the critical angle. 33. When a light ray travelling from a denser medium to the rarer medium, in this incident at the interface at an angle of incidence greater than critical angle, then light rays reflected into the denser medium, this phenomenon is known as total internal reflection 34. Sparkling of diamond, mirage and looming, shinning of the air bubble in water and optical Fibre are examples of total internal reflection. 35. The image formed by a concave mirror is generally real and inverted 32 | P a g e 36. The image formed by a convex mirror is always virtual, erect and diminished. 37. The radius of Curvature (R): The radius hollow sphere of which the mirror is a part. 38. Pole (P): The mid-point of a spherical mirror is called pole. 39. Focus (F): when a parallel beam of light rays is incident on a spherical mirror then after reflection it meets or appears to meet at a point on the principal axis, called focus of the spherical mirror. 40. Focal length (f): Focal length d= R/2 41. Prism is a uniform transparent refracting medium bounded by plane surfaces inclined at some angles forming a triangular shape. 42. When a light is incident on a glass prism, it disperses into its seven colour components in the following sequence VIBGYOR, and this is known as the dispersion of white light. 43. The refractive index of glass is maximum for violet colour 44. The refractive index of glass is minimum for the red colour 45. Rainbow is caused by dispersion of sunlight by tiny water droplets, present in the atmosphere. 46. The water droplets act like small prisms in rainbow formation. 47. The twinkling of a star is due to atmospheric refraction of starlight. 48. The apparent position of the star is slightly different from its actual position. 49. The Sun is visible to us about 2 minutes before the actual sunrise, and about 2 minutes after the actual sunset because of atmospheric refraction. 50. Hotter air is less dense and has smaller refractive index than the cooler air. 33 | P a g e 51. The earth’s atmosphere is a heterogeneous mixture of minute particles like smoke, tiny water droplets, suspended particles of dust and molecules of air. 52. When a beam of light strikes such fine particles, the path of the beam becomes visible which is known as Tyndall Effect 53. The colour of the scattered light depends on the size of the scattering particles. 54. The order of colours in light, arranged from shortest wavelength to longest, is called the visible spectrum of light. 55. Ultraviolet light and x-rays have wavelengths shorter than violet light 56. infrared (heat) and radio waves have wavelengths longer than red light. 57. The full range of wavelengths for light is called the “electromagnetic spectrum. 58. Wavelength of White Light: The white light extends from the 400 nm to 750 nm. 59. Since, the speed of light, remains constant, as frequency goes up, wavelength must go down. 60. violet has the highest frequency and the shortest wavelength of the visible colours of light. 61. red has the lowest frequency and the longest wavelength of the visible colours of light. SOUND The speed of sound in a medium depends: The temperature of the medium. 34 | P a g e The pressure of the medium. The speed of sound decreases when we go from solid to a gaseous state. In any medium, as we increase the temperature the speed of sound increases. The velocity of sound through a gas is inversely proportional to the square root of the density of the gas. Sound is mechanical energy that produces a sensation of hearing. Sound is produced due to the vibration of different objects. The sound wave propagates as compressions & rarefactions in the medium. Sound waves are longitudinal waves. Production of Sound: Sound is produced by vibrating objects. Vibration means a kind of rapid to and fro motion of an object. The sound of the human voice is produced due to vibrations in the vocal cords. Propagation of Sound: The matter or substance through which sound is transmitted is called a medium. It can be solid, liquid, or gas. Sound moves through a medium from the point of generation to the listener. Sound waves are produced due to variations in pressure & density of the medium. TYPES OF WAVES On the basis of the direction of propagation, waves can be divided into 2 types: 35 | P a g e LONGITUDINAL WAVES: In these waves, the individual particles of the medium move in a direction parallel to the direction of propagation of the disturbance. The particles do not move from one place to another but they simply oscillate back and forth about their position of rest. E.g. Sound waves. TRANSVERSE WAVES: In these waves, particles do not oscillate along the line of wave propagation but oscillate up and down about their mean position as the wave travels. E.g. Light is a transverse wave. CHARACTERISTICS OF A SOUND WAVE AND RELATED TERMS 36 | P a g e  Compression(C): These are the regions of high pressure and density where the particles are crowded and are represented by the upper portion or peak of the curve called crest. Rare-factions(R): These are the regions of low pressure and density where the particles are spread out and are represented by the lower portion of the curve called troughs or valleys. Amplitude: The magnitude of the maximum disturbance in the medium on either side of the mean value is called the amplitude of the wave. It is usually represented by the letter A. For sound, its unit will be that of density or pressure. Oscillation: It is the change in density (or pressure) from the maximum value to the minimum value and again to the maximum value. Frequency: The number of oscillations of a wave per unit time is the frequency of the sound wave. It is usually represented by ν (Greek letter, nu). Its SI unit is hertz (symbol, Hz). The larger the amplitude of vibration, the louder is the sound. The higher the frequency of vibration, the higher is the pitch, and shriller is the sound. Time Period: The time taken by two consecutive compressions or rare- factions to cross a fixed point is called the time period of the wave. It is represented by the symbol T. Its SI unit is second (s). Time Period = 1/ Frequency 37 | P a g e  Wavelength: It is the distance between two consecutive compressions or two consecutive rarefactions. The wavelength is usually represented by λ (Greek letter lambda). Its SI unit is meter (m) The speed of sound: It is defined as the distance which a point on a wave, such as a compression or a rarefaction, travels per unit of time. Speed = wavelength × frequency Range of Hearing of sound: The audible range of sound for human beings extends from about 20 Hz to 20000 Hz (one Hz = one cycle/s). Sounds of frequencies below 20 Hz are called infrasonic sound or infrasound. Rhinoceroses communicate using infrasound of frequency as low as 5 Hz. Whales and elephants produce sound in the infrasound range. Frequencies higher than 20 kHz are called ultrasonic sound or ultrasound. Ultrasound is produced by dolphins, bats, and porpoises. ULTRASOUND Ultrasounds are high-frequency waves. They are able to travel along well- defined paths even in the presence of obstacles. Ultrasounds are used extensively in industries and for medical purposes. Applications Ultrasounds can be used to detect cracks and flaws in metal blocks. Metallic components are generally used in the construction of big structures like buildings, bridges, machines, and also scientific equipment. Ultrasound is generally used to clean parts located in hard-to-reach places, for example, spiral tubes, odd-shaped parts, electronic components, etc. Ultrasonic waves are made to reflect from various parts of the heart and form the image of the heart. This technique is called ‘echocardiography’. An ultrasound scanner is an instrument that uses ultrasonic waves for getting images of internal organs of the human body. It helps the doctor to 38 | P a g e detect abnormalities, such as stones in the gall bladder and kidney or tumors in different organs. The technique is called ‘ultrasonography’. Ultrasound may be employed to break small ‘stones’ formed in the kidneys into fine grains. These grains later get flushed out with urine. SONAR The acronym SONAR stands for Sound Navigation And Ranging. Sonar is a device that uses ultrasonic waves to measure the distance, direction, and speed of underwater objects. Sonar consists of a transmitter and a detector and is installed in a boat or a ship. The transmitter produces and transmits ultrasonic waves. These waves travel through water and after striking the object on the seabed, get reflected back and are sensed by the detector. The detector converts the ultrasonic waves into electrical signals which are appropriately interpreted. The distance of the object that reflected the sound wave can be calculated by knowing the speed of sound in water and the time interval between transmission and reception of the ultrasound. Let the time interval between transmission and reception of ultrasound signal be t and the speed of sound through seawater be v. The total distance, 2d traveled by the ultrasound is then, 39 | P a g e 2d = v × t, The above method is called echo ranging. The sonar technique is used to determine the depth of the sea and to locate underwater hills, valleys, submarines, icebergs, sunken ships, etc. SUPERSONIC SOUND Again if the speed of any substance, especially of an aircraft, be more than the speed of sound in air, then the speed of the substance is called supersonic speed. INFRASONIC SOUND Sounds of frequencies below 20 Hz are called infrasonic sound or infrasound. ULTRASONIC SOUND Frequencies higher than 20 kHz are called ultrasonic sound or ultrasound. Example: Ultrasound is produced by dolphins, bats and porpoises. Applications: Ultrasounds can be used to detect cracks and flaws in metal blocks. Metallic components are generally used in the construction of big structures like buildings, bridges, machines, and also scientific equipment. The cracks or holes inside the metal blocks, which are invisible from the outside reduces the strength of the structure. Ultrasonic waves are allowed to pass through the metal block and detectors are used to detect the transmitted waves. If there is even a small defect, the ultrasound gets reflected back indicating the presence of the flaw or defect. Ultrasonic waves are made to reflect from various parts of the heart and form the image of the heart. This technique is called ‘echocardiography’. 40 | P a g e An ultrasound scanner is an instrument that uses ultrasonic waves for getting images of internal organs of the human body. A doctor may image the patient’s organs such as the liver, gall bladder, uterus, kidney, etc. It helps the doctor to detect abnormalities, such as stones in the gall bladder and kidney or tumors in different organs. In this technique, the ultrasonic waves travel through the tissues of the body and get reflected from a region where there is a change of tissue density. These waves are then converted into electrical signals that are used to generate images of the organ. These images are then displayed on a monitor or printed on a film. This technique is called ‘ultrasonography’. MACH NUMBER The ratio of the speed of a body and that of sound in air is, however, called the Mach number of the body. If the Mach number of a body is more than 1, it is clear that the body has supersonic speed. REFLECTION OF SOUND (ECHO ) It is a reflection of sound that arrives at the listener with a delay after the direct sound. The sensation of sound persists in our brain for about 0.1 seconds. To hear a distinct echo, the time interval between the original sound and the reflected one must be at least 0.1 seconds. For hearing distinct echoes, the minimum distance of the obstacle from the source of sound must be 17.2 m. This distance will change with the 41 | P a g e temperature of the air. Echoes may be heard more than once due to successive or multiple reflections. REVERBERATION The phenomenon of prolongation of sound due to successive reflections of sound from surrounding objects is called reverberation. AUDIBLE RANGE The audible range of sound for human beings extends from about 20 Hz to 20000 Hz (one Hz = one cycle/s). Children under the age of five and some animals, such as dogs can hear up to 25 kHz (1 kHz = 1000 Hz). QUICK REVISION Speed of sound approximately 332 m/sec in air at 25°C Speed of sound increases with temperature. Speed of sound ∝ temperature. At 1°C temperature rise, speed of sound rise from 0.61 m/sec. Speed of sound ∝ Humidity. So, humidity increase with increase the speed of sound. So, sound of horns (siren) can hear from very far distance in rainy season. As with any wave the speed of sound depends on the medium in which it is propagating. Sound generally travels faster in order – solids, liquids than in gases and no propagation of sound in vacuum. Frequencies from 20 Hz to 20,000 Hz are audible sound frequency. 42 | P a g e  Sound with a frequency below 20 Hz is known as an infrasonic sound. Sound with a frequency above 20,000 Hz is known as an Ultrasonic sound. The speed of sound is faster in materials that have some stiffness like steel and slower in softer materials like rubber. Factors affecting the speed of sound in air. The speed of sound in air is nearly the same for all frequencies and amplitudes. Sound is a variation in pressure. A region of increased pressure on a sound wave is called a compression (or condensation). A region of decreased pressure on a sound wave is called a rarefaction (or dilation). Unit of intensity of sound is Decibel. Upto 85 decibel sound is called Percival sound. sounds above 85 dB are harmful Normal conversation is about 60 dB The intensity of sound measured by Audio – meter. Sound wave cannot be polarized, while light wave can be polarized. Quality of sound is called pitch. There are two type of pitch: high pitch, low pitch. Reflection of sound is called “Echo”. Minimum distance to produce echo is approximate 17 meter or 56 feet. Among all gases, maximum speed of sound in “Hydrogen” (1100 m/sec). Among all metals maximum speed of sound in “aluminum” (6200 m/sec). Among all alloys maximum speed of sound in “Brass”(7200 – 8000 m/sec). Microphone: – Microphone convert sound wave into electrical energy or wave. Speaker/ loud – speaker: It convert electrical wave into sound wave. The use of microphone and speaker in telephone and mobile, which has two parts are ear piece – which convert electrical wave into sound wave, and mouth piece – which convert sound wave into electrical wave. Amplifier: – amplifier increase the amplitude of sound wave. The tape of tape recorder cassette consists of a thin plastic base material, and bonded to this base is a coating of ferric oxide powder 43 | P a g e  FORCE & MOTION A force is an interaction of the object with mass that causes the object to change its velocity. It can be defined as the push or pull on a particular object. A force is a vector quantity which means it has both magnitude and direction. When objects interact with one another, it is likely to cause a push or pull resulting in the Force. For example, when you try to push a ball, it causes a force on the ball that changes its state of motion. The external force applied has the capability to change the position of a particular object. The direction in which the force is applied is known as the direction of Force. In this post, we will discuss everything related to Force including its Formula and Types. Check out the article below to know about Force. Unit of Force The SI unit of Force is Newton(N). However, Force can also be defined in various other units as given in the table below. Common symbols: F→, F SI unit Newton In SI base units: kg·m/s2 Other units dyne, poundal, pound-force, kip, kilopond Derivations from other quantities F=ma Dimension LMT-2 Effects of Force Whenever a Force is applied on any object, it tends to change its shape, size, speed or direction. It changes the motion of an object. Motion is the 44 | P a g e movement of a body. Here are some of the effects that force has on its objects: It changes the direction of an object. It can make a body at rest to move. It can change the speed of an object by either increasing or decreasing it. It can stop a moving object. It can change the shape or size of an object. Formula of Force Force can be explained by the product of mass (m) and acceleration (a). The equation for the formula of Force can be expressed in the form as given below: F = ma Where, m = mass a = acceleration It is formulated in Newton (N) or Kgm/s2. Acceleration “a” is given by, a = v/t Where v = velocity t = time taken So Force can be defined as F = mv/t Inertia formula is termed as p = mv which can also be explained as Momentum. 45 | P a g e Types of Force There are various types of Force that act on an object. Here are some of Force applied on an object generally: Muscular Force Mechanical Force Frictional Force Gravitational Force Electrostatic Force Magnetic Force 1.Muscular Force It can be simply defined as the force that we apply on a daily basis by the work we do such as lifting, breathing, exercising etc. It acts after coming in contact with the object. This force results due to the action of our muscles. When we use our muscles to do the daily chores, muscular force is exerted on the object. 2. Mechanical Force The mechanical force occurs when there is direct contact between two objects where one object is applying the force while the other one is in a state of rest or in the state of motion. Someone pushing the door is an example of Mechanical force. 3. Frictional Force Frictional Force is the opposing force created between two surfaces whose main purpose is to create resistance to the object either moving in the same direction or opposite direction. When we put brakes while riding a cycle act as a frictional force. 4. Gravitational Force 46 | P a g e Gravitational Force is the force of attraction that attracts two objects with masses. Earth’s gravitational force pulls us to the ground. It always tries to pull the masses towards each other and never tries to push them apart. It can be defined as Newton’s Universal Law of Gravitation. 5. Electrostatic Force Electrostatic Force is also defined as the Coulomb force or Coulomb interaction. It is the force between two electrically charged objects. According to this force, like charges repel while unlike charges attract each other. Lightning is an example of the Electrostatic Force. 6. Magnetic Force Magnetic Force is the force that arises between electrically charged particles because of their motion. Magnetic force can be seen between the poles of 2 magnets. It is attractive or repulsive in nature depending upon the orientation of the object. It can be said to be a consequence of Electrostatic Forces. QUICK REVISION AND NOTES 1. Newton’s first law referred to as the law of inertia. 2. According to Newton, an object will only accelerate if there is a net or unbalanced force acting upon it. 3. Newton’s second law states that the acceleration of an object is dependent upon two variables – the net force acting upon the object and the mass of the object. A force that will work against motion in every situation is friction 4. A rocket is traveling from Earth to Mars at 10,000 m/sec. If no outside force is applied to it, its speed over the course of the trip stay constant 47 | P a g e 5. When a car suddenly stops, the objects in the back seat are thrown forward. This is due to inertia 6. If the object is NOT moving, the acceleration coming from to cause the force to increase as the mass increases is gravitational force 7. Newton’s Laws which describes the relationship between the mass and force is Law of force and acceleration 8. The tendency of an object to resist a change in motion is called inertia 9. If an object has mass, it also has inertia 10. An object with more mass has more inertia 11. My whole body doesn’t sink into the sand because the sand is pushing back up against my foot. Newton’s Third Law explains this situation. 12. Recoil of gun and motion of rocket are example of Newton’s third law 13. When two particles collide, each other experience the same force, the same impulse, and same momentum change. 14. The impulse of a force can be zero, even if the force is not zero. 15. Newton’s law of universal gravitation states that a particle attracts every other particle in the universe. 16. With a force which is directly proportional to the product of their masses 17. And this force is inversely proportional to the square of the distance between their centres. 18. F = in the given equation ‘G’ is called Universal gravitational constant 19. value of Universal gravitational constant in our world is G=67×/ 20. The direction of the force of gravity is in a straight line between two objects. It is always attractive 48 | P a g e 21. Gravitational force that sun exerts on moon is twice more than that of earth exert on it. 22. Mass is both a property of a physical body and a measure of its resistance to acceleration when a net force is applied 23. SI unit of mass is Kilogram(kg). 24. Mass of the body does not change. 25. weight of an object is related to the amount of force acting on the object, either due to gravity or to a reaction force that holds it in place 26. Mass is not the same as weight. 27. SI unit of Weight is Newton (N) 28. The acceleration which is gained by an object because of gravitational force is called its acceleration due to gravity. 29. SI unit of acceleration due to gravity is m/ 30. Momentum is the product of the mass and velocity of an object. 31. SI units, it is measured in kilogram meters per second (kg⋅m/s) 32. According to law of conservation of momentum, momentum before collision is always equal to momentum after collision. 33. The force applied on a surface in a direction perpendicular or normal to the surface is called thrust. 34. Force, and thus thrust, is measured in the International System of Units (SI) as the newton (symbol: N). 35. Pressure (symbol: p or P) is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. 49 | P a g e 36. Unit of pressure is Pascal 37. Momentum is related to Newton’s 1st 38. A person in car slides to the right when going through a very sharp left turn on the highway due to inertia. 39. The force of gravity exists between any two objects that have mass. 40. If the horse reared up on 2 legs it will exert twice the pressure it did before 41. The deeper you go under the sea, the greater the pressure of the water pushing down on you. 42. If we pull our diaphragm down, air goes into our lungs because the volume increases and so pressure 43. If we double the mass of one object, but don’t change anything else, the gravitational force between two objects doubles. 44. As distance between two objects increase the pull of gravity decreases. 45. The measure of the pull of gravity on an object is called weight. 46. If lift is going up with acceleration, the apparent weight of a body is more than the true weight. 47. An object kept in a lift which falls freely, weighs zero. 48. Pressure change occurring anywhere in a confined incompressible fluid is transmitted throughout the fluid such that the same change occurs 49. Hydraulic lift works under the principle of Pascal’s Law. 50. Jupiter is the planet with largest value of gravitational force. 51. A body will have maximum weight in Jupiter ( in the case of planets). 52. Weight of a body at poles will be higher than that at equator. 50 | P a g e 53. This is because equator will have maximum effect of centripetal force. 54. Centripetal force at poles are zero. 55. Wall of a dam is made broader at bottom to withstand the pressure that increase with depth. 56. Mano meter is used to measure liquid pressure. 57. A liquid exerts pressure in all directions. 58. If the area over which force acts is decreased, then the pressure is increased. 59. The acceleration due to gravity on the surface of the Moon is about 625 m/s2, about 16.6% that on Earth’s surface. WORK AND ENERGY QUICK NOTES 1. Fluid appears to provide partial support to the objects placed in it. 2. When a body is wholly or partially immersed in a fluid at rest, the fluid exerts pressure on the surface of the body in contact with the fluid. 3. The pressure is greater on lower surfaces of the body than on the upper surfaces as pressure in a fluid increases with depth. 4. The resultant of all the forces is an upward force called buoyant force. 5. For totally immersed objects the volume of the fluid displaced by the object is equal to its own volume. 51 | P a g e 6. If the density of the immersed object is more than that of the fluid, the object will sink as the weight of the body is more than the upward thrust. 7. If the density of the object is less than that of the fluid, it floats in the fluid partially submerged. 8. To calculate the volume of submerged part we can use this formula. Suppose the total volume of the object is Vs and a part Vp of it is submerged in the fluid. 9. Then the upward force which is the weight of the displaced fluid is ρf gVp, which must equal the weight of the body; ρs gVs= ρfgVpor ρs/ρf= Vp/Vs 10. The apparent weight of the floating body is zero. 11. Archemedes’ Principle can be summarised as; ‘the loss of weight of a body submerged (partially or fully) in a fluid is equal to the weight of the fluid displaced’. 12. Buoyancy is also known as upward thrust. 13. Buoyancy in everyday life like Swimming in water and Flying of bird or aero plane 14. Factors which affect buoyancy is Volume of the object and Density of the fluid 15. Buoyancy or upward thrust exerted by a fluid increases with the volume of the object immersed on it 16. The buoyant force or upward thrust increases with increase in density of the fluid. 17. Denser liquid exert more upward thrust. 18. This is the cause that it is easier to swim in sea water rather than fresh water 19. Salts dissolved in sea water increase the density and hence it exerts more upward thrust than fresh water 52 | P a g e 20. Mass per unit volume of an object is called density or mass density. 21. Density is denoted by Greek letter rho (ρ). 22. Density(ρ) =Mass/Volume ; Density(ρ) =m/V ; ρ = m/ V. Where, m is mass of object and V is the volume of that object. 23. SI unit of density (ρ) is kg m−3; ρ=kg/m3; (The SI unit of mass is kg and SI unit of volume is cubic meter) 24. Relative density – when density of a substance is expressed in comparison with water, it is called relative density 25. Relative density =Density of substance/Density of water 26. Relative density has no unit, because it is the ratio of similar quantity. 27. When the relative density of a substance is less than 1, it will float in water otherwise it will sink in water. 28. The relative density of ice is 0. 91, which means 9/10th of part is submerged in water. 29. Work is defined as a force acting upon an object to cause a displacement 30. It is expressed as the product of force and displacement in the direction of force. 31. W=F x s , Here, W= work done on an object F = Force on the object ; s = Displacement of the object 32. The unit of Work is Newton metre (Nm) or joule (J). 33. Joule is defined as the amount of work done by force of 1 N when displacement is 1 m. 34. When both the force and the displacement are in the same direction, positive work is done. W = F x s 53 | P a g e 35. when force acts in a direction opposite to the direction of displacement, the work done is negative. W= − F x s 36. Angle between force and displacement is 180o. 37. If force and displacement are inclined at an angle less than 180 o, then work done is given as: W= Fs cos θ 38. If force and displacement act at an angle of 90° then work done is zero. 39. Two conditions need to be satisfied for work to be done: 1) Force should act on the object. 2) Object must be displaced. 40. Work is not done when 1) A coolie carrying some load on his head stands stationary. 2) A man is applying force on a big rock. 41. Some cases force and displacement make some angle with each other is called Oblique displacement. 42. The capacity of doing work is known as energy. 43. The amount of energy possessed by a body is equal to the amount of work it can do 44. Energy is a scalar quantity; The SI unit of energy is Joule (J) 45. The various forms of energy are potential energy, kinetic energy, heat energy, chemical energy, electrical energy and light energy. 46. Kinetic Energy is the energy possessed by a body due to its motion. Kinetic energy of an object increases with its speed. 47. Kinetic energy of body moving with a certain velocity = work done on it to make it acquire that velocity 54 | P a g e 48. Examples of kinetic energy – A moving cricket ball; Running water; A moving bullet ; Flowing wind ; A moving car ; A running athlete ; A rolling stone 49. Kinetic energy is directly proportional to mass and the square of velocity. 50. Kinetic energy = 1/2 mv2 where m is the mass of the object and v is the speed of the object 51. Work = Final Kinetic energy- Initial Kinetic energy. 52. The energy possessed by a body due to its position or shape is called its potential energy. 53. Example of potential energy – Water stored in a dam has large amount of potential energy due to its height above the ground A stretched rubber band possesses potential energy due to its distorted shape. 54. Types of Potential Energy 1. Gravitational Potential Energy 2. Elastic Potential Energy 55. Gravitational Potential Energy is the energy possessed by a body due to it position above the ground. 56. Elastic Potential Energy is is the energy possessed by a body due to its change in shape. 57. The potential energy (Ep) is equal to the work done over an object of mass ‘m’ to raise it by a height ‘h’. Ep = mgh, where g = acceleration due to gravity 58. The change of one form of energy to another form of energy is known as transformation of energy. 59. Light energy can be converted into heat energy 60. Nuclear energy can be converted into light energy and heat energy 61. Solar energy can be converted into heat energy, chemical energy and electrical energy 55 | P a g e 62. Electrical energy can be converted into light energy, mechanical energy, heat energy etc 63. Thermal energy can be converted into heat energy 64. Chemical energy can be converted into electrical energy 65. Mechanical energy can be converted into electrical energy, potential energy etc 66. Gravitational potential energy can be converted into kinetic energy 67. Law of Energy Conservation – energy can neither be created nor be destroyed but transformed from one form to another. CELL Cell Theory - It states mainly three basic information: Living things are composed of one or more Cells, The cell is the basic (smallest) unit of life. It is Structural and Functional Unit of Life. & Cells arise from existing cells. Its means – Life arise from life. CELL : Many Cells make together ⇒ TISSUE Many Tissues make together ⇒ ORGAN Many Organs make together ⇒ ORGAN SYSTEM This Organ System is Called ⇒ ORGANISM 56 | P a g e Types of CELLs: Cells are of two types: 1. Prokaryotic 2. Eukaryotic Prokaryotic It do not contains a nucleus. Prokaryotes are single-celled organisms Prokaryotes include bacteria and archaea, two of the three domains of life. Prokaryotic cells were the first form of life on Earth. It does not contains Mitochondria and Chloroplasts Prokaryotes are the smallest of all organisms having size range from 0.5 to 2.0 µm in diameter. The DNA of a prokaryotic cell consists of a single circular chromosome. The nuclear region in the cytoplasm is called the nucleoid. Eukaryotic : It contains a nucleus. Plants, animals, fungi, protozoa, algae etc. all are examples of eukaryotic cells. Eukaryotes can be either single-celled or multicellular. It may contains one to several thousand Mitochondria. Algae and Plant’s Eukaryotic cell consists Chloroplasts in it. The DNA of a Eukaryotic cell consists of one or more linear molecules, called chromosomes, which are associated with histone proteins. Some Important Terms for Cell Structure: Cell Structure has a big theory. Here we will discuss only some important term for cell structure which are important for exams point of view. Please have a look: 57 | P a g e Cell nucleus - It is a cell’s information center, so it is called ‘Brain of Cell.’ A nucleus is the mostly found in a eukaryotic cell. It houses the cell’s chromosomes, and is the place where almost all DNA replication and RNA synthesis occur. The nucleus contains the cell’s DNA and directs the synthesis of ribosomes and proteins. Ribosomes: Ribosomes are responsible for protein synthesis. The ribosome is a large complex of RNA and protein molecules where RNA from the nucleus is used to synthesis proteins from amino acids. During protein synthesis, ribosomes assemble amino acids into proteins. Mitochondria : It generate energy for the cell, so Mitochondria are often called the “powerhouses” or “energy factories” of a cell because they are responsible for making adenosine triphosphate (ATP). Respiration occurs in the cell mitochondria, which generate the cell’s energy by oxidative phosphorylation, using oxygen to generate ATP. Mitochondria contain their own ribosomes and DNA; combined with their double membrane. Enzyme : It is globular protein that catalysis a biological chemical reaction. Lysosomes : It is suicide bag of a cell. Lysosomes contain digestive enzymes (acid hydro-lases). They digest excess or worn-out organelles, food particles, and engulfed viruses or bacteria. 58 | P a g e Cell wall :The cell wall acts to protect the cell mechanically and chemically from its environment, and is an additional layer of protection to the cell membrane. Different types of cell have cell walls made up of different materials:- Plant cell walls are primarily made up of Cellulose, Fungi cell walls are made up of Chitin. Bacteria cell walls are made up of Peptidoglycan. Chlorophyll : It is a green photosynthetic pigment found in plants, algae, and cyanobacteria. Chlorophyll absorbs mostly in the blue and lesser in the red portions of the electromagnetic spectrum, hence its intense color is green. Chloroplasts : Chloroplasts can only be found in plants and algae so it generate energy for their cells. They capture the sun’s energy to make carbohydrates through photosynthesis. Chromoplasts :These are colored plastids which found in fruits, flowers, roots, and leaves. Chromoplasts is reason for the color of these plant organs. Chromoplasts colored due to the pigments that are produced and stored inside them. Note: Animal cells have a Centrosome and Lysosomes while plant cells do not. Plant cells have a Cell wall, Chloroplasts and other specialized plastids, whereas animal cells do not. Important Facts of Cell for Exams : Smallest Unit of Life – Cell Structural and functional unit of Life – Cell Study of Cell is Called – Cytology 59 | P a g e  Cell word is given by – Robert Hooke Cell Theory was given by – Matthias Schleiden and Theodor Schwann First cell Discovered was – Dead Cell It was from – Cork Tissue First living cell was discovered by – Anton Van Leeuwenhoek. First living cell was a Plant Cell – Cell of Onion Smallest cell is a bacteria cell – Mycoplasma Gallisepticum Largest cell on Earth is – Ostrich Egg Longest cell in Human body – Cell of Neuron System/ Brain Cell. Power House of the cell – Mitochondria Kitchen of Plant Cell is – Chlorophyll Brain of a Cell is – Nucleus Suicide bag of a cell – Lysosomes Who is responsible for the color of Fruits and Flowers : Chromoplasts Green color of plants is due to : Chlorophyll Platform for ‘Protein Synthesis’ in cell is : Ribosomes QUICK REVISION 1. What part of the cell is responsible for breaking down and digesting things? – lysosomes 2. Who discovered cell in 1665? – Robert Hook 3. Name an Organelle which serves as a primary packaging area for molecules that will be distributed throughout the cell? – Golgi apparatus 4. Name the outer most boundary of cell? – Plasma membrane 5. Name the process in which the ingestion of material by the cells is done through the plasma membrane? – Éndocytosis 60 | P a g e 6. Which among the following sentence is not correct about the organelles? – They are found in multicellular organisms. 7. Name an organism which contains single chromosome and cell division occurs through fission or budding? – Prokaryotes 8. The jelly like substance present inside the cell is known as – Cytoplasm 9. Cell theory states that – cells are fundamental structural units of plants and animals 10. Food is converted to energy in – mitochondria 11. Ribosomes helps in – protein synthesis in cells 12. Plasma membrane is composed of – protein and lipids 13. Mitochondria was first discovered by – Altmann 14. Majority of cells cannot be seen with our naked eyes because – cells are microscopic 15. Green colour of leaves is due to presence of the pigment – chlorophyll 16. The thread like structure found in nucleus are – Chromosome 17. Who proposed the fluid mosaic model of plasma membrane – Singer and Nicolson 18. What is tonoplast in cells – membrane boundary of the vacuole of plant cells 19. Cell theory was proposed by – Schleiden and Schwann 20. Cell theory is not applicable to – Virus 21. In higher plants the shape of the chloroplast is – Discoid shape 22. The main function of centrosome is – Formation of spindle fibre 23. Plant cell wall mainly composed of – cellulose 61 | P a g e 24. The diameter of most animal cells ranges from – 10 to 100 μm. 25. What make parts of the endoplasmic reticulum rough? The presence of – Ribosome 26. Lysosomes can be expected to be present in large numbers in cells which – carryout the phagocytosis 27. Do bacteria cells have nucleus – In bacteria the genetic material dispersed in the cytosol and there is no internal membrane that delimits a nucleus 28. Death or mental retardation takes place if accumulation happens in – brain cells 29. In a normal human being number of chromosomes is – 46 30. Pigments containing bodies which are bounded by membrane are called – plastids 31. What is the fluid that fills the nucleus called? – karyolymph, or nucleoplasm 32. The first living cell was discovered by – Leeuwenhoek 33. The longest animal cell is – human nerve cell 34. The largest human cell and smallest human cell is – female ovum and RBC 35. The cell wall in fungi is composed of which one – Chitin 36. Which one is called power house of the cell – mitochondria 37. Which one is called the kitchen of the cell – Chloroplast 38. The orange colour of carrot is due to the presence of – Carotene pigment 39. Who discovered Golgi apparatus – Camillo Golgi 40. What is mean by carcinogenesis – conversion of a normal cell into cancerous cell 62 | P a g e 41. Which pigment present in the cell vacuole which provide colours to flowers – Anthocyanin 42. Which is called the unit of inheritance – Chromosomes 43. Plastids are found only in plant or animal cell ? – plant cell only 44. DNA was discovered by – James D watson and Francis Crick 45. what are the three types of RNA – 1. mRNA (messenger RNA) 2. rRNA(Ribosome RNA ) 3. tRNA (Transfer RNA) 46. The largest known cells are unfertilised is – Ostrich Egg cells (Size 6-inch diameter) 47. The red colour of tomatoes is due to the presence of which pigment – lycopene 48. Which one is the non – living matter of the cell – Deutoplasm 49. Largest unicellular plant is – Acetabularia (10 cm) 50. Who discovered the endoplasmic reticulum – KR porter 51. The inner membrane of mitochondria has many folds this is called – Cristae 52. Chloroplast is the site of which function – Photosynthesis 53. Which one is called the controlling centre of cell – Chromatin 54. Which is a result of uncontrolled mitosis cell division – Tumour or cancer 55. The mitochondria may be filamentous or granular in shape. They vary in size from – 0. 5 μm to 2. 0 μm 56. The several important functions performed by mitochondria is – oxidation, dehydrogenation, oxidativephosphorylation and respiratory chain 57. The ribosomes are spheroid structures with a diameter of – 150 to 250Å 63 | P a g e 58. The spherical organelles bounded by a single membrane. They are found in the cells of Protozoa, fungi, plants, liver and kidney of vertebrates – peroxisomes 59. The nucleus was first discovered and named by – Robert Brown 60. Chromosomes present in Gorilla is – 48 61. The study of cancer is called – Oncology 62. Lymphoma is a type of cancer. It affects which part of body – Lymphatic tissues 63. Ribosomes were discovered by – GE palade 64. Centriols and centrosomes are present only in plant or animal cell – Animal cell 65. Centrosome was discovered by – T boveri 66. In RNA which one is present in place of thyamine – Uracil 67. The main function of DNA is – It controls Heredity, Evolution, Metabolism, Structure and differentiation. 68. The main function of RNA is – protein synthesis 69. In which virus RNA is a genetic material – HIV, Reovirus 70. Most of RNA found in which part of the cell – Cytoplasm 71. The ribosome present endoplasmic reticulum is called – Rough Entoplasmic reticulum 72. Radioactive ores causes which disease in miners – Lung cancer 73. Who discovered electron microscope – Ernst Ruska and Max knoll 74. The medium which is used to mount the cleaned section on a slide – Canada balsam 64 | P a g e 75. Meiosis cell division takes place – only in diploid individuals 76. During meiosis crossing over occurs at – Diplotene 77. Prior to division each chromosome is composed of two genetically identical parts are called – Sister Chromatid DIGESTIVE SYSTEM Digestive System: A digestive system is a group of organs which work to convert the food into basic nutrients for feeding energy to the whole body. Human does not produce its own food like plants and depend on other plants and animals for food, hence called Heterotroph. Human needs various nutrients, proteins and vitamins which are derived from food through digestion. Chewing, in which food is mixed with saliva begins the process of digestion. This produces a bolus which can be swallowed down the oesophagus and into the stomach. The complete process of nutrition is divided into five stages: Ingestion Digestion Absorption Assimilation Defecation Ingestion: The process of taking food, drink or any other substance into the body by swallowing and absorbing it, is known as Ingestion. Digestion: Digestive system contains six components which are as follow- 65 | P a g e  Mouth Oesop23hagus Stomach The small intestine Colon (large intestine) Rectum Digestion is a process through the large insoluble and non-absorbable food particles are broken down into smaller water-soluble and absorbable particle which are finally absorbed by blood plasma. It is a form of catabolism which is divided into two groups based on how food is broken down in the body, if food is broken down through mechanical means then it is known as Mechanical Digestion and if it is through chemical means then it is called as Chemical Digestion. Mouth and Oesophagus Digestion initiates right from mouth, where Salivary gland secrets the Saliva in the mouth in which two types of enzymes are found, ptyalin and maltase. saliva contains an enzyme called salivary amylase that begins the process of converting starches in the food into maltose Around 1.5 litres of saliva is secreted in human on an average day, it is acidic in nature (pH 6.8) Through food pipe or Oesophagus, food reaches into the stomach. Digestion in Stomach: Ph of the stomach is 1.5-2.5. This acidic environment helps in breaking the food particle and absorption of necessary nutrients from food. The highly acidic environment of the stomach contains gastric glands which secrete gastric juice, this is a light yellow acidic acid. 66 | P a g e Pepsin and Renin are the enzymes in the gastric juice. Parietal cells secrete Chlorine and Hydrogen ion which combine to form Hydrochloric acid which helps in killing microorganisms and with the help of enzyme pepsin helps in the hydrolysis of proteins. Hydrochloric acid makes the food acidic by which ptyalin reaction of the saliva end. Pepsin breaks down the protein into peptones and Renin breaks down the Caseinogen into Casein. Digestion in Duodenum: The duodenum is the first and shortest segment of the small intestine. It receives partially digested food (known as chyme) from the stomach and plays a vital role in the chemical digestion of chyme in preparation for absorption in the small intestine. The gall bladder releases bile, which has been produced by the liver, to help further break fats down into a form that can be absorbed by the intestines. As the food reaches the duodenum bile juice from the liver combines with it. The main function of the bile juice is to convert the acidic food into alkaline, as it is alkaline in nature. Pancreatic juice from pancreas combines with food and it contains the following enzymes: Trypsin: It converts the protein and peptone into polypeptides and amino acid. Amylase: It converts the starch into soluble sugar. Lipase: It converts the emulsified fats into glycerol and fatty acids. Digestion in Small Intestine: Here the process of digestion completed and absorption of digested foods start. 67 | P a g e In the small intestine, intestinal juices secrete and it is alkaline in nature and around 2 litres of intestinal juice secretes per day. Intestinal juice contains the following enzymes: Erepsin: It converts the remaining protein and peptone into amino acids. Maltase: It converts the maltose into glucose. Sucrase: It converts the sucrose into glucose and fructose. Lactase: It converts the lactose into glucose and galactose. Lipase: It converts the emulsified fats into glycerol and fatty acids. Absorption: Digested food is absorbed by blood plasma is known as Absorption. The absorption of digested foods takes place through small intestine villi which are finger-like structure extended into the lumen of the small intestine. Assimilation: Use of absorbed food in the body or movement of digested particles where they are used is called assimilation Defecation: It is the final act of digestion. It is also known as a bowel movement. Undigested food reaches from small to the large intestine where bacterias convert it into faeces which is excreted through the anus. Disorders of the digestive system: Here are some important digestive disorder in human beings. 68 | P a g e Disorder Symptoms Vomiting Expulsion of food from the mouth due to irritation in the stomach. Diarrhoea Infectious disease resulting in a loose frequent bowel. Jaundice Yellow colouration of the skin and mucous membrane. Gall stone Cholesterol crystallises to form gall stone. Constipation difficulty of defecation due to decreased mobility in the large intestine. QUICK REVISION DIGESTIVE SYSTEM 1. The steps involved in the process of human digestive system- Ingestion, Digestion, Absorption, Assimilation and Egestion 2. The function of Hydrochloric Acid is A) It makes pepsin enzyme effective B) It kills bacteria which may enter in stomach with food line 3. The largest part of the alimentary canal is -Small intestine 4. Complete digestion of food occurs in -Small intestine 5. The bile is produced by-Liver 6. what is the function of bile juice-It makes the food alkaline 7. The hardest material present in our body is –teeth Enamel 8. In which part of our body Food gets absorbed-Small intestine 69 | P a g e 9. The undigested food stored in the liver in the form of carbohydrate is called – Glycogen 10. In humans first teeth come in between which age -6 to 8 months 11. In elephants which part is act as the incisors of upper jaw-The Tusk 12. Maximum number of teeth are present in –House and pig 13. Saliva is Secreted by which gland-Salivary glands 14. Splitting of Complex food materials into simpler molecules through the process of –hydrolysis 15. Man, and other animal have which type of Nutrition –Holozoic nutrition (Solid form of food) 16. Which converts starch into maltose(simple sugar)-Ptyalin 17. Which enzyme Digests protein and converts them into peptones –Pepsin 18. Which enzyme converts milk into curd- Renin 19. In our digestive system Ingestion of food takes place in-Buccal cavity 20. Which one is the largest salivary gland –Parotid Gland 21. Which Enzyme converts fats into fatty Acids and glycerol- lipase 22. Which one converts Sucrose into Glucose and Fructose-Sucrose 23. Which one Digests The peptides into Amino Acids-Trypsin 24. Ileum is a part of small intestine its internal surface has finger like fold to Absorbed food is called –villi 25. The PH range of Saliva and Intestinal juice is-6.8 and 8.5 respectively 26. The largest gland in our body is –Liver 70 | P a g e 27. Liver produce bile juice which is stored in which part of the body-Gall bladder 28. The functions of the liver are: a) It regulates the Quantity of glucose in the blood b) It destroys dead RBC and regulates Body temperature c) It converts Excess of Amino acid into ammonia 29. Which part of human body is important in investigation of persons death that has been due to poison in the food ?-Liver 30. The second largest gland in our human body is –Pancreas 31. Which Gland is called mixed gland (both endocrine and Exocrine)-Pancreas 32. Insulin is a hormone, which is secreted by-Beta cells in Islets of Langerhans 33. The excess of insulin causes Which disease –Hypoglycaemia 34. The Deficiency of Insulin which Causes – Diabetes mellitus 35. Which intestinal glands secretes intestinal juice-Crypts of Lieberkühn and Brunners glands 36. The human digestive system consists of alimentary canal and secondary glands. It consists of the 1) buccal cavity 2) oesophagus 3) stomach 4) small intestine 5) large intestine and 6) Anus 37. The digestion of protein starts in –Stomach 38. Duodenum has characteristic Brunners gland Which secretes two hormones called-Secretin, Chelecystokinin 39. Mucin is a glycoprotein. It helps in the lubrication of food. The lubricated Swallow able form of food is called Bolus 71 | P a g e 40. The inner wall of the stomach is lined with gastric glands. There are nearly 40million glands engaged in producing gastric juices 41. The length of small intestine is-5-7 meters long 42. Small intestine is divided into three parts names 1) Duedenum 2) Jejunum 3) Ileum 43. The longest segment in small intestine is Ileum 44. The ulcer Is mostly due to the infections by a bacterium called –Helicobacter pylori 45. Gastric gland secretes gastric juice that contains- Pepsin, Mucin, HCL 46. The children will have only how many teeth -20 47. The stomach opens into small intestine 48. The ducts of liver and pancreas unite into a common duct and open into Duodenum 49. Pancreas –It lies below the stomach. It is leaf shaped organ. It has several lobes 50. Which converts carbohydrates into maltose and Glucose –Amylase 51. The pancreatic juice contains Trypsin, Amylase and Lypase enzymes 52. Which one acts as a valve and allows only little quantities of food at a time from stomach into duodenum-Pyloric Sphincter 53. A finger like appendix is located at the base of the Caecum 54. The first part of the large intestine is Caecum. The second part of the large intestine is Colon. The last section of large intestine is Rectum 55. The exposed part of the tooth is called –Crown 72 | P a g e 56. Milk teeth of drop off at the age of -8 to 9 years 57. The teeth which develop first in the children is –milk teeth 58. The weight of the liver is -1.5 kg 59. The length of large intestine is -1.5 Mts 60. The cells of liver are called hepatic cells 61. Wisdom teeth comes out of the jaws between -17 to 25 years 62. which teeth is called wisdom teeth last molar teeth 63. Which teeth is used for cutting food during ingestion of food –Incisors 64. Which teeth helps in grinding the food –molars 65. At which side of the abdomen stomach lies ?-Left side Human Circulatory System The human circulatory system consists of a network of arteries, veins, and capillaries, with the heart pumping blood through it. Its primary role is to provide essential nutrients, minerals, and hormones to various parts of the body. Alternatively, the circulatory system is also responsible for collecting metabolic waste and toxins from the cells and tissues to be purified or expelled from the body. Features of Circulatory System The crucial features of the human circulatory system are as follows: The human circulatory system consists of blood, heart, blood vessels, and lymph. 73 | P a g e The human circulatory system circulates blood through two loops (double circulation) – One for oxygenated blood, another for deoxygenated blood. The human heart consists of four chambers – two ventricles and two auricles. The human circulatory system possesses a body-wide network of blood vessels. These comprise arteries, veins, and capillaries. The primary function of blood vessels is to transport oxygenated blood and nutrients to all parts of the body. It is also tasked with collecting metabolic wastes to be expelled from the body. Most circulatory system diagrams do not visually represent its sheer length. Theoretically, if the veins, arteries, and capillaries of a human were laid out, end to end, it would span a total distance of 1,00,000 kilometres (or roughly eight times the diameter of the Earth). Organs of Circulatory System The human circulatory system comprises 4 main organs that have specific roles and functions. The vital circulatory system organs include: Heart Blood (technically, blood is considered a tissue and not an organ) Blood Vessels Lymphatic system Heart The heart is a muscular organ located in the chest cavity, right between the lungs. It is positioned slightly towards the left in the thoracic region and is enveloped by the pericardium. The human heart is separated into four chambers; namely, two upper chambers called atria (singular: atrium), and two lower chambers called ventricles. 74 | P a g e Heart, a major part of the human circulatory system Though other animals possess a heart, the way their circulatory system functions is quite different from humans. Moreover, in some cases, the human circulatory system is much more evolved when compared to insects or molluscs. Double Circulation The way blood flows in the human body is unique, and it is quite efficient too. The blood circulates through the heart twice, hence, it is called double circulation. Other animals like fish have single circulation, where blood completes a circuit through the entire animal only once. The main advantage of double circulation is that every tissue in the body has a steady supply of oxygenated blood, and it does not get mixed with the deoxygenated blood. Blood Blood is the body’s fluid connective tissue, and it forms a vital part of the human circulatory system. Its main function is to circulate nutrients, hormones, minerals and other essential components to different parts of the body. Blood flows through a specified set of pathways called blood vessels. The organ which is involved in pumping blood to different body parts is the heart. Blood cells, blood plasma, proteins, and other mineral components (such as sodium, potassium and calcium) constitute human blood. Blood is composed of: Plasma – the fluid part of the blood and is composed of 90% of water. Red blood cells, white blood cells and platelets constitute the solid part of blood. 75 | P a g e Types of Blood Cells The human body consists of three types of blood cells, namely: Red blood cells (RBC) / Erythrocytes Red blood cells are mainly involved in transporting oxygen, nutrients, and other substances to various parts of the body. These blood cells also remove waste from the body. White blood cells (WBC) / Leukocytes White blood cells are specialized cells, which function as a body’s defence system. They provide immunity by fending off pathogens and harmful microorganisms. Platelets / Thrombocytes Platelets are cells that help to form clots and stop bleeding. They act on the site of an injury or a wound. Blood Vessels Blood vessels are a network of pathways through which blood travels throughout the body. Arteries and veins are the two primary types of blood vessels in the circulatory system of the body. Arteries Arteries are blood vessels that transport oxygenated blood from the heart to various parts of the body. They are thick, elastic and are divided into a small network of blood vessels called capillaries. The only exception to this is the pulmonary arteries, which carries deoxygenated blood to the lungs. Veins Veins are blood vessels that carry deoxygenated blood towards the heart from various parts of the body. They are thin, elastic and are present 76 | P a g e closer to the surface of the skin. However, pulmonary and umbilical veins are the only veins that carry oxygenated blood in the entire body. Lymphatic System The human circulatory system consists of another body fluid called lymph. It is also known as tissue fluid. It is produced by the lymphatic system which comprises a network of interconnected organs, nodes and ducts. Lymph is a colourless fluid consisting of salts, proteins, water, which transport and circulates digested food and absorbed fat to intercellular spaces in the tissues. Unlike the circulatory system, lymph is not pumped; instead, it passively flows through a network of vessels. Functions of Circulatory System The most important function of the circulatory system is transporting oxygen throughout the body. The other vital functions of the human circulatory system are as follows: It helps in sustaining all the organ systems. It transports blood, nutrients, oxygen, carbon dioxide and hormones throughout the body. It protects cells from pathogens. It acts as an interface for cell-to-cell interaction. The substances present in the blood help repair the damaged tissue. QUICK REVISION 1. _________ is a special connective tissue consisting of a fluid matrix, plasma, and formed elements – blood 77 | P a g e 2. What are needed for clotting or coagulation of blood – fibrinogens 3. Plasma without the clotting factors is called – Serum 4. The liquid part of the blood is called – Plasma 5. Three important plasma proteins are – albumin, globulin, fibrinogen 6. The red pigment in RBCs that carries oxygen is called – Haemoglobin 7. The term ______ is used to describe a number of disease conditions caused by the inability of RBCs to carry a sufficient amount of oxygen – Anemia. 8. If the body produces an excess of RBCs, the condition is called- Polycythemia. 9. What type of WBCs, produce antibodies to fight microbes – B lymphocytes 10. P