caie-as-level-physics-9702-theory-64481818120a31078602077e-989.pdf

ZNOTES.ORG UPDATED TO 2022-2024 SYLLABUS CAIE AS LEVEL PHYSICS SUMMARIZED NOTES ON THE THEORY SYLLABUS Prepared for Rahmah Rizwan for personal use only. CAIE AS LEVEL PHYSICS Multiples 1. Physical Quantities and...

ZNOTES.ORG UPDATED TO 2022-2024 SYLLABUS CAIE AS LEVEL PHYSICS SUMMARIZED NOTES ON THE THEORY SYLLABUS Prepared for Rahmah Rizwan for personal use only. CAIE AS LEVEL PHYSICS Multiples 1. Physical Quantities and Multiple Prefix Symbol Units 12 10 Tera (T ) 9 10 Giga (G) 6 1.1. Physical Quantities 10 Mega (M ) 3 10 Kilo (k) All physical quantities consist of a numerical magnitude ㅤ Sub-Multiplesㅤ Sub-multiple Prefix Symbol and a unit: 10 −3 Milli (m) 10 −6 Micro (μ) Estimating Physical Quantitiesㅤ 10 −9 Nano (n) Quantity Estimate 10 −12 Pico (p) Height of an Adult Human 2m The mass of an adult human 70 kg 1.3. Errors and Uncertainties Mass of a car 1000 kg Systematic Errors: Power of a lightbulb 60 W Constant error in one direction: too big or too small Errors made by instruments used and wrong Speed of sound in air 330 ms−1 techniques Speed of a car on the motorway 30 ms−1 It cannot be eliminated by repeating or averaging Weight of an apple 1N If systematic error is small, measurement is accurate Density of water 1000 kgm−3 Accuracy: the degree of agreement between the result of a measurement and the true value of Time taken for a sprinter to run 10 s quantity. 100m Random Errors: Current in a domestic appliance 13 A Random fluctuations or scatter about a true value E.M.F of a car battery 12 V Caused by the observers and environmental techniques Atmospheric pressure 1.0 × 10 5 P a This can be reduced by repeating and averaging Young’s modulus of a given material Something × 10 11 When random error is small, measurement is precise Precision: the degree of agreement of repeated 1.2. SI Units measurements of the same quantity (regardless of whether it is close to the true value or not) Quantity Base Unit Calculations Involving Errorsㅤ Mass (m) Kilogram (kg) Length (l) Meter (m) For a quantity x = (5.0 ± 0.2)mm Time (t) Second (s) Absolute Uncertainty Δx = ±0.2mm Temperature (T ) Kelvin (K ) Fractional Uncertainty = Δx x = 0.04 ​ Electric Current (I ) Ampere (A) Percentage Uncertainty = Δx x × 100% = 4% ​ Combining errors: ㅤ When values are added or subtracted, add absolute error All units (excluding those above) can be broken down into 2x+y 2x−y 2Δx+Δy If p = 3 or p = 3 ​,then Δp = 3 the base units ​ ​ ​ When values are multiplied or divided, add % errors Homogeneity can be used to prove equations. When values are raised to a certain power (e.g., An equation is homogenous if base units on the left side squared), multiply the percentage error by the power are the same as those on the right side. If r = 2xy 3 , then Δr Δx r = x + y 3Δy ​ ​ ​ WWW.ZNOTES.ORG Copyright © 2024 ZNotes Education & Foundation. All Rights Reserved. This document is authorised for personal use only by Rahmah Rizwan at undefined on 14/08/24. CAIE AS LEVEL PHYSICS 1.4. Scalars and Vectors Scalar: has magnitude only, cannot have direction e.g., speed, energy, power, work, mass, distance Vector: has magnitude and direction e.g., displacement, acceleration, force, velocity momentum, weight, electric field strength 2.4. Non-Linear Motion Both scalars and vectors have magnitude and unit. Velocity-time graph: Gradient = acceleration The area under graph = change in displacement Uniform acceleration and straight-line motion equations: v = u + at s = ut + 12 at2 = vt − 12 at2 ​ ​ s = 12 (u + v ) tv 2 = u 2 + 2as ​ A force vector can be split into its vertical and horizontal Acceleration of free fall = 9.81ms-2 components, which are independent. Pythagoras theorem (a2 + b2 = c 2 ) and vector 2.5. Motion of Freefalling Bodies parallelograms can add coplanar vectors. 2. Kinematics Continues 2.1. Kinematics Concepts to curve as Displacement it Distance: total length moved irrespective of direction accelerates Displacement: shortest distance in a certain direction Speed: distance traveled per unit of time, no direction Velocity: the rate of change of displacement Acceleration: the rate of change of velocity Graph levels off as 2.2. Equations of Motions it reaches terminal s = ut + 12 at2 velocity ​ v = u + at v 2 = u 2 + 2as s = (v1 +2 v2 ) × t ​ ​ ​ 2.3. Linear Motion Continues to Velocity Distance: total length moved irrespective of direction accelerate Displacement: distance in a certain direction constantly Speed: distance traveled per unit of time, no direction Velocity: the rate of change of displacement Acceleration: the rate of change of velocity Displacement-time graph: Gradient = velocity WWW.ZNOTES.ORG Copyright © 2024 ZNotes Education & Foundation. All Rights Reserved. This document is authorised for personal use only by Rahmah Rizwan at undefined on 14/08/24. CAIE AS LEVEL PHYSICS Continues to curve as Displacement it accelerates Graph curves as it decelerates and levels off to terminal velocity Acceleration Straight line s = ut + 12 at2 and u = 0 ; s = 12 at2 i.e h = 12 gt2 ​ ​ ​ Graph curves 2.7. Projectile motion down to zero Projectile motion: uniform velocity in one direction and because the constant acceleration in perpendicular direction resultant force equals zero 2.6. Determining Acceleration of Free Fall A steel ball is held on an electromagnet. When the electromagnet is switched off, the ball interrupts a light beam, and a timer starts. As the ball falls, it interrupts a second beam of light & timer stopped Vertical distance h is plotted against t2 Horizontal motion = constant velocity (speed at which projectile is thrown) Vertical motion = constant acceleration (caused by the weight of the object, constant free fall acceleration) Curved path – parabolic (y ∝ x2 ) Component of Velocity Horizontal Vertical Without air Increases at a constant Constant Resistance rate WWW.ZNOTES.ORG Copyright © 2024 ZNotes Education & Foundation. All Rights Reserved. This document is authorised for personal use only by Rahmah Rizwan at undefined on 14/08/24. CAIE AS LEVEL PHYSICS Component of Velocity Mass: is a measure of the amount of matter in a body, & is the property of a body that resists change in motion. Decreases to Increases to a constant With Air resistance Weight: is the force of gravitational attraction (exerted by zero value the Earth) on a body. 2.8. Motion of a Skydiver 3.4. Elastic Collisions Total momentum conserved Total kinetic energy is conserved Example: Two identical spheres collide elastically. Initially, X is moving with speed v and Y is stationary. What happens after the collision? 3. Dynamics 3.1. Newton’s Laws of Motion X stops and Y moves with speed v: (relative velocity before collision) = (relative velocity after First Law: if a body is at rest, it remains at rest, or if it is in collisions) motion, it moves with a uniform velocity until it is acted on u A ​− u B ​= vB ​− vA by resultant force or torque ​ ​ ​ ​ Second Law: the rate of change of momentum of a body is proportional to the resultant force and occurs in the 3.5. Inelastic Collisions direction of force; F = ma Third Law: if a body A exerts a force on a body B , then relative speed of approach > relative speed of separation body B exerts an equal but opposite force on body A, Total momentum is conserved forming an action-reaction pair Total kinetic energy is not conserved Perfectly inelastic collision: only momentum is conserved, 3.2. Momentum and the particles stick together after collision (i.e. move with the same velocity) Linear Momentum: product of mass and velocity In inelastic collisions, total energy is conserved but Ek ​ ​ may be converted into other forms of energy e.g. heat p = mv Force: rate of change of momentum 3.6. Collisions in Two Dimensions mv − mu F = t ​ ​ Principle of Conservation of Linear Momentum: when bodies in a system interact, total momentum remains constant, provided no external force acts on the system. mA u A + mB u B = mA vA + mB vB ​ ​ ​ ​ ​ ​ ​ 3.3. Mass and Weight Mass Weight Measured in kilograms Measured in Newtons Scalar quantity Vector quantity Constant throughout the universe Not constant W = mg WWW.ZNOTES.ORG Copyright © 2024 ZNotes Education & Foundation. All Rights Reserved. This document is authorised for personal use only by Rahmah Rizwan at undefined on 14/08/24. CAIE AS LEVEL PHYSICS Change in momentum (impulse) affecting each sphere acts along line of impact Law of conservation of momentum applies along line of impact Components of velocities of spheres along plane of impact unchanged Note the direction of the velocities when calculating 4. Forces, Density, and Pressure Forces on masses in gravitational fields: a region of space in which a mass experiences an (attractive) force due to 4.1. Introduction the presence of another mass. Forces on charge in electric fields: a region of space Force: rate of change of momentum where a charge experiences an (attractive or repulsive) Density: mass per unit of volume of a substance force due to the presence of another charge. Pressure: force per unit area Upthrust: an upward force exerted by a fluid on a Finding resultant (nose to tail): submerged or floating object By accurate scale drawing Origin of Upthrust: Using trigonometry Pressure on Bottom Surface > Pressure on Top Surface ∴ Force on Bottom Surface > Force on Top Surface ⇒ Resultant force upwards Frictional force: force that arises when two surfaces rub Always opposes relative or attempted motion Always acts along a surface Value varies up to a maximum value Viscous forces: A force that opposes the motion of an object in a fluid; Only exists when there is motion. Its magnitude increases with the speed of the object Centre of gravity: point through which the entire weight of the object may be considered to act Couple: a pair of forces which produce rotation only To form a couple: WWW.ZNOTES.ORG Copyright © 2024 ZNotes Education & Foundation. All Rights Reserved. This document is authorised for personal use only by Rahmah Rizwan at undefined on 14/08/24. CAIE AS LEVEL PHYSICS Equal in magnitude 5.3. Gravitational, Elastic and Electric Parallel but in opposite directions Separated by a distance d Potential Energy Moment of a Force: product of the force and the perpendicular distance of its line of action to the pivot Gravitational Potential Energy: ㅤ Energy possessed by a mass due to its position in the gravitational field ㅤM oment = F orce × ⊥Distance from P ivot Arises in a system of masses where there are ㅤ attractive gravitational forces between them. Elastic potential energy: Torque of a Couple: the product of one of the forces of the Energy stored in a body due to a change in its shape couple and the perpendicular distance between the lines Arises in a system of atoms where there are attractive of action of the forces. / repulsive short-range inter-atomic forces between ㅤ them Electric potential energy: T orque = F orce × ⊥Distance between F orces Arises in a system of charges where there are ㅤ attractive / repulsive electric forces between them Conditions for Equilibrium: The resultant force acting on it in any direction equals 5.4. Deriving Gravitational Potential zero. The resultant torque about any point is zero. Energy Principle of Moments: for a body to be in equilibrium, the sum of all the anticlockwise moments about any point W = F s & w = mg = F must be equal to the sum of all the clockwise moments ∴ W = mg.s about that same point. s in direction of force = h above ground ∴ W = mgh 4.2. Pressure in Fluids 5.5. Deriving Kinetic Energy Fluids refer to both liquids and gases Particles are free to move and have EK ∴ they collide ​ W = F s & F = ma with each other and the container. This exerts a small ∴ W = ma.s force over a small area causing pressure to form. v 2 = u 2 + 2as ⟹ as = 1 (v 2 − u2 ) 2 ​ ∴ W = m. 12 (v 2 − u 2 ) ​ Derivation of Pressure in Fluids ∴ W = 12 mv 2 ​ Volume of water = A × h 5.6. Internal Energy Mass of Water == density × volume = ρ × A × h Weight of Water == mass × g = ρ × A × h × g Internal energy: sum of the K.E. of molecules due to its Pressure = Force ρ×A×h×g Area =​ A ​= ρgh​ random motion & the P.E. of the molecules due to the intermolecular forces. Gases: k.e. > p.e. 5. Work, Energy, Power Molecules far apart and in continuous motion = k.e Weak intermolecular forces so very little p.e. 5.1. Energy Conservation Liquids: k.e. ≈ p.e. Molecules able to slide to past each other = k.e. Law of Conservation of Energy: the total energy of an Intermolecular force present and keep shape = p.e. isolated system cannot change—it is conserved over time. Solids: k.e. < p.e. Energy can be neither created nor destroyed but can Molecules can only vibrate ∴ k.e. very little change form, e.g. from g.p.e to k.e Strong intermolecular forces p.e. high 5.2. Work Done 5.7. Power and Efficiency Work done by a force: the product of the force and Power: work done per unit of time displacement in the direction of the force W= Fs P ower = Work Done Time Taken ​​ WWW.ZNOTES.ORG Copyright © 2024 ZNotes Education & Foundation. All Rights Reserved. This document is authorised for personal use only by Rahmah Rizwan at undefined on 14/08/24. CAIE AS LEVEL PHYSICS Deriving it to form P = Fv Measure diameter of wire using micrometer screw gauge Set up arrangement as diagram: P = W.d T ​& W.d. = F s ​ ∴ P = Fs s T = F ( t )​ ​ ​ ∴ P = Fv Efficiency: ratio of (useful) output energy of a machine to the input energy Useful Energy Ouput Efficiency = Total Energy Input ​ × 100 Attach weights to end of wire and measure extension 6. Deformation of Solids 6.1. Stress and Strain Deformation is caused by a force Tensile force Act away from each other, object stretched out and increased in length (extension) Compressive force Calculate Young’s Modulus using formula Act towards each other, object squashed and decreased in length (compression) 6.4. Stress, Strain and Young’s Modulus Stress: the force applied per unit cross-sectional area σ= F A ​( N ​ m −2 ​or Pascals) Strain: fractional increase in original length of wire ε = xl ​(no units) ​ Young’s Modulus: ratio of stress to strain E= σ ε ​in N ​ m −2 ​or Pascals Stress-Strain Graph: 6.2. Elastic and Plastic Behaviour A spring produces an extension when a load is attached Hooke’s law: the extension produced is proportional to the applied force (due to the load) as long as the limit of proportionality hasn't been reached. F = ke Where k is the spring constant (unit: force per unit extension); e is the extension. Limit of proportionality: the point beyond which the extension is no longer proportional to the force Calculating effective spring constants: Gradient = Young’s modulus Area under the curve = work done per unit volume = energy Series Parallel stored per unit volume 1 1 1 kE ​ = k1 ​ + k2 ​ ​ kE = k1 + k2 ​ ​ ​ ​ Elastic deformation: when deforming forces are removed, ​ ​ the spring returns back to its original length 6.3. Determining Young’s Modulus WWW.ZNOTES.ORG Copyright © 2024 ZNotes Education & Foundation. All Rights Reserved. This document is authorised for personal use only by Rahmah Rizwan at undefined on 14/08/24. CAIE AS LEVEL PHYSICS Plastic deformation: when deforming forces are removed, 7.3. Phase Difference the spring does not return to its original length Elastic limit: maximum stress that can be applied before Phase difference between two waves is the difference in causing plastic deformation terms of fraction of a cycle or in terms of angles (A B) Force-Extension Graph: Wave A leads wave B by θ or Wave B lags wave A by θ Phase difference = xλ × 2π (unit: radians or degrees) ​ Gradient = Spring constant The area under the curve = work done = strain energy stored Strain energy: the potential energy stored in or work done by an object when it is deformed elastically In phase (in step): phase difference = 0, 2π , …, 2nπ Strain energy = area under force-extension graph Antiphase: phase difference = π , 3π , …, (2n + 1)π W = 12 F x = 12 kx 2 7.4. Wave Graphs ​ ​ 7. Waves 7.1. Progressive Waves Wave motion: a propagation of disturbance that travels from one location to another. Displacement: distance of a point from its undisturbed (equilibrium) position Amplitude: maximum displacement of a particle from an undisturbed position Period: time taken for one complete oscillation Frequency: number of oscillations per unit time 1 f= T​ ​ Wavelength: distance from any point on the wave to the next precisely similar point (e.g. crest to crest) Displacement-distance graph: for a fixed time Wave speed: speed at which the waveform travels in the Displacement-time graph: for a fixed position direction of the propagation of the wave Progressive waves transfer energy from one position to another. 7.5. Cathode-Ray Oscilloscope 7.2. Deducing Wave Equation Speed = Distance ​ Time ​ Distance of 1 wavelength is λ and time taken for this is T ∴ v = Tλ ​ f = T1 ​so v = fλ ​ WWW.ZNOTES.ORG Copyright © 2024 ZNotes Education & Foundation. All Rights Reserved. This document is authorised for personal use only by Rahmah Rizwan at undefined on 14/08/24. CAIE AS LEVEL PHYSICS Source moving away from Observer: Change in wavelength leads to change in frequency Observed frequency (f0 ) is different from actual ​ frequency (fs ​); related by equation: ​ fs v f0 = ​ v±vs ​ ​ ​ source moves towards observer: v − vs ,​f0 increases; ​ ​ blue shift source moves away observer: v + vs ,​f0 decreases; red ​ ​ shift where v is speed of wave and vs ​is speed of source relative ​ Used to determine frequency and amplitude to observer Y-gain: increase in voltage per unit (determine amplitude) Time-base: increase in time per unit (determine period 7.8. Transverse and Longitudinal waves and frequency) Transverse Waves 7.6. Intensity Oscillation of wave particles perpendicular to direction of propagation Rate of energy transmitted per unit area perpendicular to Polarization can occur direction of wave propagation (unit: W m −2 ) E.g. light waves Power Intensity = Cross Sectional Area ​ Intensity ∝ Amplitude 2 Power Power For a point source: Intensity = Cross Sectional Area = 4πr 2 ​ ​ ∴ Intensity ∝ r12 ​ ∴ Amplitude ∝ r1 ​ 7.7. The Doppler Effect Arises when source of waves moves relative to observer Can occur in all types of waves, including sound & light Source stationary relative to Observer: Longitudinal Waves Oscillations of wave particle parallel to direction of propagation Polarization cannot occur E.g. sound waves Source moving towards Observer: 7.9. Polarization WWW.ZNOTES.ORG Copyright © 2024 ZNotes Education & Foundation. All Rights Reserved. This document is authorised for personal use only by Rahmah Rizwan at undefined on 14/08/24. CAIE AS LEVEL PHYSICS 8.2. Interference and Coherence Interference: the superposition of two or more waves in similar or same direction to give a resultant wave whose amplitude is given by the principle of superposition. Coherence: same type of waves having same frequency/wavelength and a constant phase difference. Constructive Two sources in-phase: path difference = nλ Two sources anti-phase: path difference = n λ2 ​ Destructive Two sources in-phase: path difference = n λ2 ​ Two sources anti-phase: path difference = nλ Polarization: the action of restricting the vibration of a transverse wave wholly or partially to one direction. ONLY transverse waves can be polarized. Malus’ Law: I = I 0 c os2 θ ​ A = A0 c osθ , I ∝ A2 ​ where I is the intensity, A is the amplitude, θ is the angle between the transmission axis of the polaroid and the plane of the incident polarized wave. 7.10. Electromagnetic Waves As electromagnetic wave progresses, wavelength decreases and frequency increases n = 1, 2, 3, … 8.3. Two-Source Interference Visible light: 400 nm - 700 nm All electromagnetic waves: All travel at the speed of light: 3 ∗ 10 8 ms− 1 Travel in free space (don’t need medium) Can transfer energy Are transverse waves 8. Superposition Conditions for Observable Two-Source Interference: 8.1. Principle of Superposition Meet at a point Must be of the same type When two or more waves of the same type meet at a Must be coherent point, the resultant displacement is the algebraic sum of Must be unpolarized or have the same plane of the individual displacements polarization WWW.ZNOTES.ORG Copyright © 2024 ZNotes Education & Foundation. All Rights Reserved. This document is authorised for personal use only by Rahmah Rizwan at undefined on 14/08/24. CAIE AS LEVEL PHYSICS Must have approximately the same amplitude Stationary waves will be produced by the direct and Demonstrating Two-Source Interference: reflected waves in the string. Water Ripple generators in a tank Light Double slit interference Microwaves Two microwave emitters 8.4. Formation of Stationary waves Microwaves: A stationary wave is formed when two progressive waves A microwave emitter placed a distance away from a metal of the same frequency, amplitude and speed, travelling in plate that reflects the emitted wave. opposite directions are superposed. By moving a detector along the path of the wave, the Node: region of destructive superposition where waves nodes and antinodes could be detected. always meet out of phase by π , ∴ displacement = zero (closed end) Antinode: region of constructive superposition where waves meet in phase ∴ particle vibrate with max amplitude (open end) Air Columns: A tuning fork held at the mouth of an open tube projects a sound wave into the column of air in the tube. The length can be changed by varying the water level. Neighboring nodes & antinodes separated by 12 λ ​ At certain lengths tube, the air column resonates Between 2 adjacent nodes, particles move in phase; they This is due to the formation of stationary waves by the are out of phase with the particles between the next two incident and reflected sound waves at the water surface. nodes by π Node always formed at surface of water Stationary waves cannot transfer energy. Stationary wave at different times: 8.5. Stationary Wave Experiments 8.6. Stationary and Progressive Waves Stretched String: String either attached to wall or attached to weight Stationary Waves Progressive Waves WWW.ZNOTES.ORG Copyright © 2024 ZNotes Education & Foundation. All Rights Reserved. This document is authorised for personal use only by Rahmah Rizwan at undefined on 14/08/24. CAIE AS LEVEL PHYSICS Stationary Waves Progressive Waves Stores energy (cannot Transmits energy transfer energy) Have nodes & antinodes No nodes & antinodes Amplitude increases from Amplitude constant along node to antinode length of the wave Phase change of π at node No phase change 8.7. Diffraction Diffraction: the spreading of waves as they pass through a narrow slit or near an obstacle For diffraction to occur, the size of the gap should be equal to the wavelength of the wave. ax λ= D​ ​ Where a = split separation D = distance from slit to screen x = fringe width If white light is used: Central fringe is white: all wavelengths are in step Other fringes show colored effects: different wavelength (red light will be further than violet light because λ red > λ violet ) ​ ​ Increase amplitude of one Decrease amplitude of one source source fringe spacing does not fringe spacing does not change change bright fringes are brighter bright fringes are darker dark fringes are darker dark fringes are brighter Experimental Arrangement Add a single slit before the double slit: ensure that the Gap Width Amount of diffraction two waves are coherent (needed when using light >> λ smallest bulbs). λ < Gap < 2λ limited Use lasers: light is more concentrated; light is monochromatic (makes fringes clearer); no single slit ≤λ greatest needed. 8.8. Double-Slit Interference 8.9. Diffraction Grating WWW.ZNOTES.ORG Copyright © 2024 ZNotes Education & Foundation. All Rights Reserved. This document is authorised for personal use only by Rahmah Rizwan at undefined on 14/08/24. CAIE AS LEVEL PHYSICS V2 P = V I ; P = I 2R ; P = R ​ P = Power V = Voltage I = Current R = Resistance 9.2. Current-Carrying Conductors d sin θ = nλ 1 Where d = distance between successive slits = N ​ N = number of slits per meter θ = angle from horizontal equilibrium n = order number Electrons move in a certain direction when p.d. is applied λ = wavelength across a conductor causing current double-slit diffraction grating Deriving a formula for current: closely spaced bright widely spaced bright Q I= t ​ pattern fringes on a dark fringes on a dark ​ background background Q t L brighter and sharper vol. of container = LA time needed = t = v​​ (more slits: more light No. of free electrons = nLA features less bright and sharp pass through; narrower Total charge = Q = nLAq slits: more diffracted) nLAq ∴I = L ​ ​ 9. Electricity v ​ I = Anvq Where L = length of conductor A = cross-sectional area of conductor 9.1. Introduction n = no. free electrons per unit volume q = charge on 1 electron Electric Current: the flow of charged particles v = average electron drift velocity Charge at a point. Product of the current at that point and the time for which the current flows, 9.3. Resistance and Resistivity Q = It Resistance: defined as the ratio of the potential difference Q = Charge, I = Current, t = time taken to flow through to the current (unit: Ω ) point Coulomb: charge flowing per second passes a point at R= V I ​ which the current is one ampere −1 Charge is Quantised: charge values are not continuous; Ohm is defined as volt per ampere ( Ω = VA ) they are discrete. Ohm’s Law: the current in a component is proportional to All charges are multiples of charge of 1e: 1.6 × 10 −19 C the potential difference across it provided physical Potential Difference: two points have a potential conditions (e.g. temp) stay constant difference of 1V if the work required to move 1C of charge Ohmic Component: obeys Ohm’s law between them is 1 joule R = ρLA ​ Volt: joule per coulomb ρ = resistivity (constant for the same material at constant temperature; unit: Ωm ) W =VQ L = length W = Work Done A = cross-sectional area V = Voltage Q = Charge 9.4. I-V Characteristics WWW.ZNOTES.ORG Copyright © 2024 ZNotes Education & Foundation. All Rights Reserved. This document is authorised for personal use only by Rahmah Rizwan at undefined on 14/08/24. CAIE AS LEVEL PHYSICS Metallic Conductor Ohmic conductor V/I constant Temperature constant Semi-Conductor Diode Non-ohmic conductor Low resistance in one direction and infinite resistance in opposite Threshold voltage: the voltage at which the diode suddenly starts to conduct \n Filament Lamp Non-ohmic conductor Volt ↑ Temp. ↑ Vibration of ions ↑ Collision of ions with e- ↑ Resistance ↑ Light Dependent Resistor (LDR) Light intensity ↑ Resistance ↓ 10. D.C. Circuits 10.1. Potential Difference and Electromotive Force Electromotive Force: the amount of energy given to each Thermistor (Negative Temperature Coefficient) coulomb of charge to go around the circuit once. Non-ohmic conductor Potential difference (work done per unit charge) Volt ↑ energy transformed from electrical to other forms per Temp. ↑ unit charge Released e- ↑ Electromotive force (work done per unit charge) Resistance ↓ energy transformed from other forms to electrical 10.2. Internal Resistance Internal Resistance: resistance to current flow within the power source; reduces p.d. when delivering current WWW.ZNOTES.ORG Copyright © 2024 ZNotes Education & Foundation. All Rights Reserved. This document is authorised for personal use only by Rahmah Rizwan at undefined on 14/08/24. CAIE AS LEVEL PHYSICS The voltage across resistor: V = IR Voltage lost to internal resistance: V = E − I r Usage of a thermistor at R1: Thus e.m.f.: E = I R + I r Resistance decreases with increasing temperature. E = I (R + r) It can be used in potential divider circuits to monitor and control temperatures. Usage of an LDR at R1: 10.3. Kirchhoff’s 1st Law Resistance decreases with increasing light intensity. It can be used in potential divider circuits to monitor The sum of currents in a junction light intensity. IS EQUAL TO The sum of currents out of the junction. 10.8. Potentiometers Kirchhoff’s 1st law is another statement of the law of conservation of charge A potentiometer is a continuously variable potential divider used to compare potential differences Potential difference along the wire is proportional to the 10.4. Kirchhoff’s 2nd Law length of the wire It can be used to determine the unknown e.m.f. of a cell Sum of e.m.f.s in a closed circuit IS EQUAL TO This can be done by moving the sliding contact along the wire until it finds the null point that the galvanometer Sum of potential differences shows a zero reading; the potentiometer is balanced Kirchhoff’s 2nd law is another statement of the law of conservation of energy Example: E1 is 10 V, and and distance XY equals 1m. The potentiometer is balanced at point T, which is 0.4m from X. Calculate E2 10.5. Deriving Effective Resistance in Series From Kirchhoff’s 2nd Law: E = ∑ IR I R = I R1 + I R2 ​ ​ ​ Current constant therefore cancel: R = R1 + R2 ​ ​ ​ 10.6. Deriving Effective Resistance in Parallel E1 E2 = LLXY ​ ​ ​ XT ​ ​ ​ ​ From Kirchhoff’s 1st Law: 10 1 E2 = 0.4 ​ ​ ​ I = ∑I ​ E2 = 4 V ​ I = I1 + I2 ​​ ​ V V V R = R1 + R2 ​ ​ ​ ​ ​ ​ 10.9. Circuit Symbols Voltage constant therefore cancel: 1 1 1 R ​ = R1 ​ ​ + R2 ​​ ​ 10.7. Potential Divider A potential divider divides the voltage into smaller parts. WWW.ZNOTES.ORG Copyright © 2024 ZNotes Education & Foundation. All Rights Reserved. This document is authorised for personal use only by Rahmah Rizwan at undefined on 14/08/24. CAIE AS LEVEL PHYSICS 11. Nuclear Physics 11.1. Geiger-Marsden α Experiment: a beam of α -particles is fired at thin gold foil WWW.ZNOTES.ORG Copyright © 2024 ZNotes Education & Foundation. All Rights Reserved. This document is authorised for personal use only by Rahmah Rizwan at undefined on 14/08/24. CAIE AS LEVEL PHYSICS Random: impossible to predict and each nucleus has the same probability of decaying per unit time Spontaneous: not affected by external factors such as the presence of other nuclei, temperature and pressure Evidence on a graph: Random; graph will have fluctuations in count rate Spontaneous; graph has same shape even at different temperatures, pressure etc. 11.4. Radiations α-particle β-particle γ-ray Helium Fast-moving Identity Electromagnetic nucleus electron/positron Symbol 4 0 − 0 + 0 2 He​ −1 e / 1 e ​ ​ 0γ​ Charge +2 −1 0 Relative 4 1/1840 0 Mass Slow ( v of light ( 3 × Speed Fast ( 10 8 ms−1 ) 10 6 ms−1 ) 10 8 ms−1 ) Continuous range (because Results of the experiment: Energy Discrete (anti)neutrinos are Most particles pass straight through emitted in β-decay) Some are scattered appreciably Few mm of Very few – 1 in 8,000 – suffered deflections > 90º Stopped by Paper Few cm of lead aluminium Conclusion: Most of an atom is empty space Ionizing High Low Very Low All mass and charge concentrated in the center of power atom ∴ nucleus is small and very dense Effect of Deflected Deflected greater Undeflected Nucleus is positively charged as α -particles are Magnetic slightly repelled/deflected Effect of Attracted Attracted to +ve Undeflected Electric to -ve 11.2. The Nuclear Atom Force Strong Weak interaction interaction Nucleon number: total number of protons and neutrons Proton/atomic number: total number of protons 11.5. Types of Decays Isotope: atoms of the same element with a different number of neutrons but the same number of protons α decay: loses a helium nucleus Simple model: A X → A−4 X + 4 α The nucleus is made of protons and neutrons. Z ​ Z−2 2 ​ ​ β − decay: neutron turns into a proton and an electron & Electrons move around the nucleus in a cloud, some electron antineutrino are emitted closer to and some further from the nucleus. A A 0 − Nuclide notation: A Z X → Z+1 X + −1 e + B \n u} ZX ​ ​ ​ d → u + 0−1 e− + B A: nucleon number ​ Z: proton number β + decay: proton turns into a neutron and a positron & X: element electron neutrino are emitted A X → A X + 0 e+ + \n u Unified atomic mass unit: u Z ​ Z−1 1 ​ ​ 1 1 u = 12​mass of a carbon-12 atom u → d + 01 e+ + \n u ​ γ decay: a nucleus changes from a higher energy state to a lower energy state through the emission of 11.3. Nuclear Processes electromagnetic radiation (photons) During a nuclear process, nucleon number, proton number and mass-energy are conserved 11.6. Fundamental Particles Radioactive process are random and spontaneous WWW.ZNOTES.ORG Copyright © 2024 ZNotes Education & Foundation. All Rights Reserved. This document is authorised for personal use only by Rahmah Rizwan at undefined on 14/08/24. CAIE AS LEVEL PHYSICS Fundamental Particle: a particle that cannot be split up Antiquark Symbol Charge into anything smaller Anti-Up u − 23 e Electron is a fundamental particle but protons and ​ neutrons are not Anti-Down d + 13 e ​ Protons and neutrons are made up of different combinations of smaller particles called quarks These antiquarks combine to similarly form respective Table of Quarks: antiprotons and antineutrons Quark Symbol Charge 11.7. Particle Families Up u + 23 e ​ Down d − 13 e ​ Charm c + 23 e ​ Strange s − 13 e ​ Top t + 23 e ​ Bottom b − 13 e ​ Quark Models: Proton Neutron Hadrons: made up of quarks Leptons: fundamental particles Baryons: made up of 3 quarks of 3 antiquarks Mesons: made up of 1 quark & 1 antiquark 2 Up & 1 Down 1 Up & 2 Down + 23 e + 23 e − 13 e = +e ​ ​ ​ + 23 e − 13 e − 13 e = 0 ​ ​ ​ All particles have their corresponding antiparticle (same mass, opposite charge) Table of Antiquarks: WWW.ZNOTES.ORG Copyright © 2024 ZNotes Education & Foundation. All Rights Reserved. This document is authorised for personal use only by Rahmah Rizwan at undefined on 14/08/24. CAIE AS LEVEL Physics © ZNotes Education Ltd. & ZNotes Foundation 2024. All rights reserved. This version was created by Rahmah Rizwan on 14/08/24 for strictly personal use only. 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