PHYSICS QB 2024.pdf

SENIOR SCHOOL CERTIFICATE EXAM - 2024 PHYSICS 1|Page  DAV PUBLIC SCHOOLS, ODISHA, ZONE-D SAMPLE PAPER 1/5  Please check that this question paper contains 9 printed pages.  Set number given on...

SENIOR SCHOOL CERTIFICATE EXAM - 2024 PHYSICS 1|Page  DAV PUBLIC SCHOOLS, ODISHA, ZONE-D SAMPLE PAPER 1/5  Please check that this question paper contains 9 printed pages.  Set number given on the right hand side of the question paper should be written on the title page of the answer book by the candidate.  Check that this question paper contains 33 questions.  Write down the Serial Number of the question in the left side of the margin before attempting it.  15 minutes cooling time has been allotted to read this question paper. The question paper will be distributed 15 minutes prior to the commencement of the examination. The students will read the question paper only and will not write any answer on the answer script during this period. CLASS – XII SUB: PHYSICS (042) Time:3 Hours Maximum Marks:70 General Instruction: 1. The question paper comprises FIVE sections -A, B, C, D and E. 2. All the sections are compulsory. Section A contains sixteen question, twelve MCQ and four assertion reason question of 1 mark each. 3. Section-B comprises five questions of 2 marks each, Section-C comprises seven questions of 3 marks each, and Section-D contains two case study based questions of four marks each and Section-E comprises three questions of 5 marks each. 4. There is no overall choice. However, an internal choice has been provided in section B, C, D and E. You have to attempt only one of the choices in such questions. 5. Use of calculator is not allowed. (SECTION-A) 1. An electric dipole is a. a pair of electric charges of equal magnitude q but positive sign, separated by a distance d b. a pair of electric charges of equal magnitude q but opposite sign, separated by a distance d c. a pair of electric charges of equal magnitude q but negative sign, separated by a distance d d. a pair of electric charges of equal magnitude q separated by a distance d 2. Equipotential surfaces (a) are closer in regions of large electric fields compared to regions of lower electric 2|Page  fields. (b) Will be more crowded near sharp edges of a conductor. (c) Will always be equally spaced. (d) Both (a) and (b) are correct. 3. Which of the following statements is false for a perfect conductor? (a) The surface of the conductor is an equipotential surface. (b) The electric field just outside the surface of a conductor is perpendicular to the surface. (c) The charge carried by a conductor is always uniformly distributed over the surface of the conductor. (d) None of these. 4. Current flows through uniform, square frames as shown in the figure. In which case is the magnetic field at the centre of the frame not zero? 5. Two identical current carrying coaxial loops, carry current I in opposite sense. A simple amperian loop passes through both of them once. Calling the loop as C, then which statement is correct? (c) There may be a point on C where B and dl are parallel. (d) None of these 6. A cell having an emf E and internal resistance r is connected across a variable external resistance R. As the resistance R is increased, the plot of potential difference V across R is given by 7. A current carrying power line carries current from west to east. What will be direction of magnetic field 1 meter above it? (a) N to S (b) S to N (c) E to W (d) W to E 3|Page 8.The magnetic field is parallel to a surface, then the magnetic flux through the surface is : (a) zero (b) small but not zero (c) infinite (d) large but not infinite 9. What happens if one of the slits, say S1 in Young’s double, slit experiment-is covered with a glass plate which absorbs half the intensity of light from it? (a) The bright fringes become less-bright and the dark fringes have a finite light intensity (b) The bright fringes become brighter and the dark fringes become darker (c) The fringe width decreases (d) No fringes will be observed 10. What happens to the interference pattern the two slits S 1 and S2 in Young’s double experiment are illuminated by two independent but identical sources? (a) The intensity of the bright fringes doubled (b) The intensity of the bright fringes becomes four times (c) Two sets of interference fringes overlap (d) No interference pattern is observed 11. The strength of photoelectric current depends upon: (a) angle of incident radiation (b) frequency of incident radiation (c) intensity of incident radiation (d) distance between anode and cathode 12. When a yellow light is incident on a surface, no electrons are emitted while green light can emit electrons. If the red light is incident on the surface then: (a) no electrons are emitted (b) photons are emitted (c) electrons of higher energy are emitted (d) electrons of lower energy are emitted A/R QUESTION Each of these questions contain two statements, Assertion and Reason. Each of these questions also has four alternative choices, only one of which is the correct answer. You have to select one of the codes (a), (b), (c) and (d) given below. (a) Assertion is correct, reason is correct; reason is a correct explanation for assertion. (b) Assertion is correct, reason is correct; reason is not a correct explanation for assertion (c) Assertion is correct, reason is incorrect (d) Assertion is incorrect, reason is correct. 13. Assertion: In series LCR resonance circuit, the impedance is equal to the ohmic resistance. Reason: At resonance, the inductive reactance exceeds the capacitive reactance. 14. Assertion: A capacitor is connected to a direct current source. Its reactance is infinite. Reason: Reactance of a capacitor is given by χc = 1/ωC. 15. Assertion: Electromagnetic waves interact with matter and set up oscillations. Reason: Interaction is independent of the wavelength of the electromagnetic wave. 16. Assertion : The force of repulsion between atomic nucleus and α-particle varies with distance according to inverse square law. Reason : Rutherford did α-particle scattering experiment. (SECTION-B) 4|Page 17. (a) An electrostatic field line is a continuous curve. That is, a field line cannot have sudden breaks. Why not? (b) Explain why two field lines never cross each other at any point? OR. Two balls have same kind of charge attracts each other. Explain. 18. Define neutral point. Draw lines of force when two identical magnets are placed at a finite distance apart with their N-poles facing each other. Locate the neutral points.. 19. A screen is placed 90 cm from an object. The image of the object on the screen is formed by a convex lens at two different locations separated by 20 cm. Determine the focal length of the lens. 20.How will the interference pattern in Young’s double-slit experiment get affected, when (a) distance between the slits S1, and S2 reduced and (b) the entire set-up is immersed in water? Justify your answer in each case. 21. An electron and alpha particle have the same de-Broglie wavelength associated with them. How are their kinetic energies related to each other? OR The figure shows a plot of three curves a, b, c, showing the variation of photocurrent vs. collector plate potential for three different intensities I1, I2 and I3 having frequencies V1, v2 and v3 respectively incident on a photosensitive surface. Point out the two curves for which the incident radiations have same frequency but different intensities. (SECTION-C) 22.(a) In what respect is a toroid different from a solenoid? Draw and compare the pattern of the magnetic field lines in the two cases. (b) How is the magnetic field inside a given’ solenoid made strong? 23. (a) Obtain the expression for the magnetic energy stored in a solenoid in terms of the magnetic field B, area A and length l of the solenoid. (b) How is this magnetic energy per unit volume compared with the electrostatic energy per unit volume stored in a parallel plate capacitor? 24. Why are infrared radiations referred to as heat waves also? Name the radiations which are next to these radiations in the electromagnetic spectrum having (a) Shorter wavelength and (b) Longer wavelength. (c)Find the wavelength of electromagnetic waves of frequency in free space. Give its two applications. OR 5|Page In a plane electromagnetic wave, the electric field oscillates sinusoid ally with a frequency of and amplitude 48V/m. (a) What is the wavelength of the em. wave? (b) Calculate the amplitude of the oscillating magnetic field. (c) Calculate average energy density of the electromagnetic field of the wave? 25.Two lines, A and B, in the plot given below show the variation of de-Broglie wavelength, λ versus 1/√ V, Where V is the accelerating potential difference, for two particles carrying the same charge. Which one of two represents a particle of smaller mass? 26. Using Bohr’s postulates of the atomic model, derive the expression for radius of nth electron orbit. Hence obtain the expression for Bohr’s radius. OR In Rutherford scattering experiment, draw the trajectory traced by a-particles in the coulomb field of target nucleus and explain how this led to estimate the size of the nucleus. 27. Distinguish between an intrinsic semiconductor and p-type semiconductor. Give reason, why, a p-type semiconductor crystal is electrically neutral although n h >> ne? 28. Draw a plot of the potential energy of a pair of nucleons as a function of their separations. Mark the regions where the nuclear force is (i) attractive and (ii) repulsive. Write any two characteristic features of nuclear forces. (SECTION-D) 29. When p side of p-n junction is connected to positive terminal of battery and n side of p-n junction is connected to negative terminal of battery then the p-n junction is said to be in forward bias mode or forward biased. And When p side of p-n junction is connected to negative terminal of battery and n side of p-n junction is connected to positive terminal of battery then the p-n junction is said to be in reverse bias mode or reverse biased. The diode used to rectify an AC voltage is called as rectifier. Zener diode is also a p-n junction diode which works in reverse bias condition and used as voltage regulator. Also, p-n junction diodes are used in solar cells which is used to convert light energy into electrical energy. Light emitting diodes are also p-n junction diodes which are used to produce light. 6|Page i. Which among the following is the most commonly used semiconductor? a. Silicon b. Carbon c. Germanium d. Sulphur ii. What happens to the resistance of a pure semiconductor when heated? a. The resistance increases b. The resistance decreases c. The temperature remains the same d. Can’t say iii. How many valence electrons does a pentavalent impurity have? a.3 b. 4 c. 5 d. 6 OR iv. Which of the following does a hole in the semiconductor define? a. A free proton. b. A free neutron c. A free-electron d. An incomplete part of an electron pair bond v. With fall of temperature, the forbidden energy gap of a semiconductor (a) increases (b) decreases (c) sometimes increases and sometimes decreases (d) remains unchanged 30.It consists of two converging lenses placed coaxially. The one facing the distant object is called the objective and has a large aperture and a large focal length. The other is called the eyepiece, as the eye is placed close to it. It has a smaller aperture and a smaller focal length. The lenses are fixed in tubes. The eyepiece tube can slide within the objective tube so that the separation between the objective and the eyepiece may be changed. (i)When light travels from a rarer medium to denser medium, the speed of light decreases. Then which of the following property remains unchanged? 7|Page  a)Velocity b)Wave length c)Frequency d)None of these ii) The objective lenses of two telescopes have the same apertures but their focal lengths are in the ratio 1: 2.If both the telescopes have same eyepiece focal length what will be the ratio of their magnifying power in normal adjustment? a)1:2 b)2:1 c)4:1 d)1:4 iii) A refracting telescope at an observatory has an objective lens of focal length 1.5 m. If an eyepiece lens of focal length 1.0 cm is used, the tube length of the telescope in normal adjustment is a)1.6m b)160cm c)1.51m d)1.15m OR If this telescope is used to view distant object at least distance of distinct vision the its magnifying power will be a)156 b)150 c)165 d)200 (iv)The tube lengths of a telescope whose focal length of the objective is 20 cm and magnification in normal adjustment of 10 is a)12cm b)30cm c)22cm d)32cm (SECTION-E) 31. (a) Write a relation between current and drift velocity of electrons in a conductor. Use this relation to explain how the resistance of a conductor changes with the rise in temperature (b)In the following arrangement of capacitors, the energy stored in the 6 μF capacitor is E. Find the value of the following. (a) Energy stored in 12 pF capacitor. (b) Energy stored in 3 pF capacitor. (c) Total energy drawn from the battery. OR (a) Obtain the expression for the potential due to an electric dipole of dipole moment p at a point ‘x’ on the axial line. (b) Two identical capacitors of plate dimensions l × b and plate separation d have dielectric slabs filled In between the space of the plates as shown In the figures. Obtain the relation between the dielectric constants K, K1, and K2. 32.(a)Use Kirchhoff’s rules to determine the value of the current I1 flowing in the 8|Page circuit shown in the figure. (b)A uniform wire of resistance 12 Ω is cut into three pieces so that the ratio of the resistances R1 : R2 : R3 = 1 : 2 : 3 and the three pieces are connected to form a triangle across which a cell of emf 8V and internal resistance 1 Ω is connected as shown. Calculate the current through each part of the circuit OR (I)State Kirchhoff’s rules. Explain briefly how these rules are justified. (II): A network of resistors is connected to a 16 V battery with internal resistance of 1Ω, as shown in Fig: (a) Compute the equivalent resistance of the network. (b) Obtain the current in each resistor. (c) Obtain the voltage drops VAB, VBC and VCD. 33.(i)A small telescope has an objective lens of focal length 140 cm and an eyepiece of focal length 5.0 cm. What is the magnifying power of the telescope for viewing distant objects when (a) the telescope is in normal adjustment (i.e., when the final image is at infinity)? (b) The final image is formed at the least distance of distinct vision (25 cm)? (ii)Draw a labeled diagram for a refracting type astronomical telescope. How will its magnifying power be affected by increasing for its eyepiece (a) the focal length and (,b) the aperture? Justify your answer. Write two drawbacks of refracting type telescopes. OR (i)Draw a labeled ray diagram of a Newtonian type reflecting telescope. Write any one advantage over refracting type telescope. (ii)A right-angle crown glass prism with a critical angle of 41° is placed between the 9|Page object PQ in two positions as shown in figures (a) and (b). Trace the path of rays from P and Q passing through the prisms in the two cases. 10 | P a g e  DAV PUBLIC SCHOOLS, ODISHA ZONE - D SAMPLE PAPER - 2/5 (2023-24)  Please check that this question paper contains 08 printed pages.  Set number given on the right hand side of the question paper should be written on the title page of the answer book by the candidate.  Check that this question paper contains 33 questions.  Write down the Serial Number of the question in the left side of the margin before attempting it.  15 minutes time has been allotted to read this question paper. The question paper will be distributed 15 minutes prior to the commencement of the examination. The students will read the question paper only and will not write any answer on the answer script during this period. CLASS- XII SUB : PHYSICS (42) Time : 3 Hours Maximum Marks :70 General Instructions : (1) There are 33 questions in all. All questions are compulsory. (2) This question paper has five sections: Section A, Section B, Section C, Section D and Section E. (3) All the sections are compulsory. (4) Section A contains sixteen questions, twelve MCQ and four Assertion Reasoning based of 1 mark each, Section B contains five questions of two marks each, Section C contains seven questions of three marks each, Section D contains two case study based questions of four marks each and Section E contains three long answer questions of five marks each. (5) There is no overall choice. However, an internal choice has been provided in one question in Section B, one question in Section C, one question in each CBQ in Section D and all three questions in Section E. You have to attempt only one of the choices in such questions. (6) Use of calculators is not allowed. (7) You may use the following values of physical constants where ever necessary i. c = 3 x 108 m/s ii. me = 9.1 x10-31 kg iii. e = 1.6 x 10-19 C iv. μ0 = 4π x 10-7 Tm𝑨−𝟏 v. h = 6.63 x10-34 Js vi. ε0 = 8.854 x10-12 𝑪𝟐𝑵−𝟏𝒎−𝟐 vii. Avogadro’s number = 6.023 X 𝟏𝟎𝟐𝟑 per gram mole SECTION-A Q.NO MARK( QUESTION. S) The value of minimum force acting between two charges placed at 1 m apart from each other is: 1 (a)Ke2 (b)2Ke 2 (c) 4Ke2 (d)Ke2/2 1 2 The effective capacitance of the system is: 1 11 | P a g e  (a) C (b) 2C (c) 3C (d) 2C/3 A beam of light converges at a point P. Now a lens is placed in the path of the convergent beam 3 12cm from P. The point at which the beam converge if the lens is a concave lens of focal length 1 16cm is: (a) 38cm (b) 4cm (c) 48cm (d) 28cm An electron emitted by a heated cathode and accelerated through a potential difference of 2000V, 4 enters a region with uniform magnetic field of 0.15T. The radius of trajectory of the electron if the 1 field is transverse to its initial velocity is: (a) 1mm (b) 5mm (c) 2cm (d) 1.5mm An α- particle of energy 5 MeV is scattered through 180 by a fixed uranium nucleus. The distance 0 5 of closest approach is of the order of : 1 (a) 10A (b) 10-10 cm (c) 10-12 cm (d) 10-15 cm Figure shows a small magnetised needle P placed at a point O. The arrow shows the direction of its magnetic moment. The other arrows show different positions (and orientations of the magnetic moment) of another identical magnetised 6 1 needle Q. The configuration corresponds to the lowest potential energy among all the configurations shown is: (a) PQ1 (b) PQ4 (c) PQ3 (d) PQ6 In Fig. Vo is the potential barrier across a p-n junction, when no battery is connected across the junction (a) 1 and 3 both correspond to forward bias of junction 7 (b) 3 corresponds to forward bias of junction and 1 1 corresponds to reverse bias of junction (c) 1 corresponds to forward bias and 3 corresponds to reverse bias ofjunction. (d) 3 and 1 both correspond to reverse bias of junction. Electrons used in an electron microscope are accelerated by a voltage of 25 kV. If the voltage is 8 increased to 100 kV then the de-Broglie wavelength associated with the electrons would be : 1 (a) increase by 2 times (b) decrease by 2 times (c) decrease by 4 times (d) increase by 4 times The direction of induced currents in metal rings 1 and 2 when current I in the wire is decreasing steadily are: 9 (a) 1-clockwise, 2-anticlockwise 1 (b) 2-clockwise, 1-anticlockwise (c) 2-clockwise, 1-clockwise (d) 1-anticlockwise, 2-anticlockwise Diffusion current in a p-n junction is greater than the drift current in magnitude 10 (a) if the junction is forward-biased 1 (b) if the junction is reverse-biased (c) if the junction is unbiased 12 | P a g e  (d) in no case. The energy level diagram of an element is given. Identify, by doing necessary calculations, which transition corresponds to the emission of a spectral line of wavelength 102.7 nm? 11 1 (a) A (b) B (c)C (d) D Highly energetic electrons are bombarded on a target of an element containing 30 neutrons. The 12 ratio of radii of nucleus to that of Helium nucleus is (14)1/3. The atomic number of nucleus will be: 1 (a)25 (b)26 (c)56 (d)30 Assertion Reasoning based Question For Questions 13 to 16, two statements are given – one labelled Assertion (A) and other labelled Reason (R). Select the correct answer to these questions from the options as given below. (a) If both Assertion and Reason are true and Reason is correct explanation of Assertion. (b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion. (c) If Assertion is true but Reason is false. (d) If both Assertion and Reason are false. Assertion(A) : If the length of the conductor is doubled, the drift velocity will become half of the 13 original value (keeping potential difference unchanged). 1 Reason(R) : At constant potential difference, drift velocity is inversely proportional to the length of the conductor. Assertion(A): Faraday’s laws are consequence of the conservation of energy. 14 Reason(R): The presence of large magnetic flux through a coil maintains a current in the coil, if 1 the circuit is continuous. Assertion(A):- For circuits used for transporting electric power, a low power factor implies large 15 power loss in transmission. 1 Reason(R): Power factor can often be improved by the use of a capacitor of appropriate capacitance in the circuit. Assertion(A) :The magnetic field B at a point in between the plates of a parallel-plate   r dE capacitor during charging is 0 0 (symbols having usual meaning). 16 2 dt 1 Reason(R): The magnetic field B is due to conduction current flowing between the plates of capacitor. SECTION-B The resistance of the platinum wire of a platinum resistance thermometer at the ice point is 5 Ω and 17 at steam point is 5.25 Ω. When the thermometer is inserted in a hot bath, the resistance of the 2 platinum wire is 5.5 Ω. Find the temperature of the hot bath in Celsius scale. A rod of length l is moved horizontally with a uniform velocity ‘v’ in a direction perpendicular to 18 its length through a region in which a uniform magnetic field is acting vertically downward. Derive 2 the expression for the emf induced across the ends of the rod. 13 | P a g e  OR Define self-inductance of a coil. Show that magnetic energy required to build up the current I in a coil of self-inductance L is given by (½) LI2. Two wavelengths of sodium light 590 nm and 596 nm are used in turn to study the diffraction at a 19 single slit of size 4 mm. The distance between the slit and screen is 2 m. Calculate the separation 2 between the positions of the first maximum of the diffraction pattern obtained in the two cases. Explain with the help of a diagram, how a depletion layer and barrier potential are formed in a 20 junction diode. 2 Draw a plot of the binding energy per nucleon as a function of mass number for a large number of 21 nuclei, 2 ≤ A ≤ 240. How do you explain the constancy of binding energy per nucleon in the range 2 30 < A < 170. SECTION-C (a) Explain briefly, with the help of circuit diagram, the working of a full wave rectifier. Draw its 22 input and output waveforms 3 The network PQRS, shown m the circuit diagram, has the batteries of 5 V and 10 V and negligible internal resistance. A milliammeter of 50Ω resistance is connected between P 23 and R. Calculate the reading in the milliammeter 3 (a) In what way is diffraction from each slit related to the interference pattern in a double slit experiment? (b) The ratio of the widths of two slits in Young’s double slit experiment is 9 : 4. Evaluate the ratio of intensities at maxima and minima in the interference pattern OR (a)In Young’s double slit experiment, monochromatic light of wavelength 630 nm illuminates the 24 3 pair of slits and produces an interference pattern in which two consecutive bright fringes are separated by 8.1 mm. Another source of monochromatic light produces the interference pattern in which the two consecutive bright fringes are separated by 7.2 mm. Find the wavelength of light from the second source. (b) When monochromatic light is incident on a surface separating two media, the reflected and refracted light both have the same frequency as the incident frequency. Explain why? You are given three lenses L1 L2 and L3 each of focal length 20 cm. An object is kept at 40 cm in front of 25 3 L1, as shown. The final real image is formed at the focus I of L3. Find the separations between L1, L2 and L3. Using the graph shown in the figure for stopping potential v/s the incident frequency of photons, 26 calculate 3 (a)Planck’s constant. 14 | P a g e  (b)work function The value of ground state energy of hydogen atom is -13.6 eV and Bohr radius is 0.53Å. Calculate 27 (i) the energy required to move an electron from the ground state to the second excited state. (ii) 3 (a) the kinetic energy and (b) the orbital radius in the second excited state of the atom. Suppose that the electric field part of an electromagnetic wave in vacuum is 28 E = {(3.1 N/C) cos [(1.8 rad/m) y + (5.4 × 108 rad/s)t]}ˆi. 3 (a) What is the wavelength λ (b) What is the frequency ν ? (c) Write an expression for the magnetic field part of the wave. SECTION-D (Case Based Question) Q.NO. QUESTION When electric dipole is placed in uniform electric field, its two charges experience equal and opposite forces, which cancel each other and hence net force on electric dipole in uniform 29 electric field is zero. However these forces are not collinear, so they give rise to some torque on the dipole. Since net force on electric dipole in uniform electric field is zero, so no work is done in moving the electric dipole in uniform electric field. However some work is done in rotating the dipole against the torque acting on it. An electric dipole consists of two opposite charges, each of magnitude 1.0 μC separated by a (i) distance of 2.0 cm. The dipole is placed in an external field of 105 NC-1. The maximum torque on 1 the dipole is: (a) 0.2 x 10-3 Nm (b) 1x 10-3 Nm (c) 2 x 10-3 Nm (d) 4x 10-3 Nm Torque on a dipole in uniform electric field is minimum when θ is equal to: (a) 0° (b) 90° (c) 180° (d) Both (a) and (c) (ii) OR 1 The dipole moment of a dipole in a uniform external field Ē ⃗ is p ⃗. Then the torque τ acting on the dipole is (a) τ = p x E (b) τ = P. E (c) τ = 2(p + E) (d) τ = (P + E) When an electric dipole is held at an angle in a uniform electric field, the net force F (iii) and torque τ on the dipole are: 1 (a) F= 0, τ = 0 (b) F≠0, τ≠0 (c) F=0, τ ≠ 0 (d) F≠0, τ=0 An electric dipole of moment p is placed in an electric field of intensity E. The dipole acquires a position such that the axis of the dipole makes an angle with the direction of the field. Assuming that potential energy of the dipole to be zero when 0 = 90°, the torque and the potential energy of (iv) 1 the dipole will respectively be: (a) pEsinθ, - pEcosθ (b) pEsinθ, -2pEcosθ (c) pEsinθ, 2pEcosθ (d) pEcosθ, – pEsinθ 15 | P a g e  The simplest and the most widely used capacitor is the parallel plate capacitor. It consists of two large plane parallel conducting plates, separated by a small distance.In the outer regions above the upper 30 plate and below the lower plate, the electric fields due to the two charged plates cancel out. The net field is zero.In the inner region between the two capacitor plates, the electric fields due to the two charged σ plates add up. The net field is ε0. For a uniform electric field, potential difference between the plates = Electric field x distance between the plates. Capacitance of the parallel plate capacitor is, the charge required to supplied to either of the conductors of the capacitor so as to increase the potential difference between them by unit amount. A parallel plate capacitor is charged and then isolated. The effect of increasing the plate separation (i) on charge, potential and capacitance respectively are 1 (a) increases, decreases, decreases (b) constant, increases, decreases (c) constant, decreases, decreases (d) constant, decreases, increases In a parallel plate capacitor, the capacity increases 1 (ii) (a) area of the plate is decreases (b) distance between the plates increases (c) area of the plate is increases (d) dielectric constant decreases A parallel plate capacitor has two square plates with equal and opposite charges. The surface (iii) charge densities on the plates are +σ and −σ respectively. In the region between the plates the 1 magnitude of the electric field is (a) σ/2ε0 (b) σ/ε0 (c) o (d) none of these. If a parallel plate air capacitor consists of two circular plates of diameter 8 cm. At what distance should the plates be held so as to have the same capacitance as that of sphere of diameter 20 cm? a) 9mm (b)4 mm (c) 8 mm (d) 2mm (iv) OR 1 If a charge of + 2.0 x 10-8 C is placed on the positive plate and a charge of -2.0 x 10-8 C on the negative plate of a parallel plate capacitor of capacitance 1 nF then the potential difference developed between the plates is (a) 6.25 V b) 3.0 V (c) 20 V (d) 25 V SECTION-E (a) Draw a labelled ray diagram showing the image formation of a distant object by a refracting telescope. Deduce the expression for its magnifying power when the final image is formed at infinity. (b) The sum of focal lengths of the two lenses of a refracting telescope is 105 cm. The focal length of one lens is 20 times that of the other. Determine the total magnification of the telescope when 31 the final image is formed at infinity. 5 OR (a)Draw a ray diagram to show the formation of the image of an object placed on the axis of a convex refracting surface, of radius of curvature R, separating the two media of refractive indices n1 and n2 (n2 > n1). Use this diagram to deduce the relation n2/v−n1/u = (n2−n1)/R where u and v represent respectively the distance of the object and the image formed. 16 | P a g e  (b) The radii of curvature of the faces of a double convex lens are 10 cm and 15 cm. If focal length of the lens is 12 cm, find the refractive index of the material of the lens. (a) Write, using Biot-Savart law, the expression for the magnetic field B due to an element dl carrying current I at a distance r from it in a vector form. Hence derive the expression for the magnetic field due to a current carrying loop of radius R at a point P distant x from its centre along the axis of the loop. (b) The maximum current that can be measured by a galvanometer of resistance 40 Ω is 10 mA. It is converted into voltmeter that can read upto 50 V. Find the resistance to be connected in the series 5 32 with the galvanometer. OR (a) Derive the expression for the torque on a rectangular current carrying loop suspended in a uniform magnetic field. (b) A solenoid of 50 cm long has 4 layers of windings of 350 turns each.If the current carried is 6 A, then find the magnetic field at the centre of the solenoid. (a)A series LCR circuit is connected to an ac source, V(t) = Vm sin t. Using the phasor diagram, derive the expression for the impedance of the circuit. (b) A device ‘X’ is connected to an a.c source. The variation of voltage, current and power in one complete cycle is shown in Fig (i)Which curve shows power consumption over a full cycle? 33 5 (ii)Identify the device ‘X’ OR (a)Draw a labelled diagram of a transformer. Obtain the expression for ratio of secondary to primary voltage in terms of number of turns and currents in the two coils. (b) Kamla peddles a stationary bicycle the pedals of the bicycle are attached to a 100 turn coil of area 0.10 m2. The coil rotates at half a revolution per second and it is placed in a uniform magnetic field of 0.01 T perpendiculars to the axis of rotation of the coil. What is the maximum voltage generated in the coil? 17 | P a g e  DAV PUBLIC SCHOOLS, ODISHA ZONE-D SAMPLE PAPER-3/5 (2023-24) CLASS-XII SUBJECT-PHYSICS Time Allowed: 3 hours Maximum Marks: 70 Marks. General Instructions: (1) There are 33 questions in all. All questions are compulsory. (2) This question paper has five sections: Section A, Section B, Section C, Section D and Section E. (3) All the sections are compulsory. (4) Section A contains sixteen questions, twelve MCQ and four Assertion Reasoning based of 1 mark each, Section B contains five questions of two marks each, Section C contains seven questions of three marks each, Section D contains two case study based questions of four marks each and Section E contains three long answer questions of five marks each. (5) There is no overall choice. However, an internal choice has been provided in one question in Section B, one question in Section C, one question in each CBQ in Section D and all three questions in Section E. You have to attempt only one of the choices in such questions. (6) Use of calculators is not allowed.. Q. SECTION A MARKS NO. 1 What is the electric field intensity at the centre of a charged metallic sphere of radius is 1 10metre ,if the potential on its surface is 60volt ? (i) 600 V/m (ii) 6 V/m (iii) 120 V/m (iv) 0V/m 2 The electric potential on the surface of a metallic sphere of radius 10cm is V volt. Then the 1 potential at the centre of the sphere will be (i) 2V (ii)V (iii)V/2 (iv)Zero 3 A cell of emf E and internal resistance r has its terminals connected to a resistance R such 1 that the potential difference between the terminals is 1. 6 V when R = 4 Ω and 1.8 V when R = 9 Ω. Then, (i) E = 1 V, r = 1 Ω (ii) E = 2. 5 V, r = 0.5Ω (iii) E = 2 V, r = 1 Ω (iv) E = 2 V , r = 2 Ω 4 An electron is projected towards east in earth’s magnetic field. 1 Then it will be deflected towards (i)Vertically Up (ii)Vertically down (iii)North (iv)South 5 A long straight wire of circular cross section of radius ‘a’ carries a steady current I. The 1 current is uniformly distributed across its cross section. The ratio of the magnitudes of magnetic field at a point distant a/2 above the surface of wire to that at a point distant ‘a/2’ below its surface is (i) 4 :1 (ii)1:1 (iii)4: 3 (iv)3 :4 18 | P a g e 6 If the magnetizing field on a ferromagnetic material is increased,its permeability 1 (i) Decreases ( ii)increases (iii)remains unchanged (iv)first decreases and then increases 7 An iron cored coil is connected in series with an electric bulb with an AC source as shown 1 in figure. When iron piece is taken out of the coil, the brightness of the bulb will (i)decrease (ii)increase (iii)remain unaffected (iv)fluctuate 8 Which of the following electromagnetic waves are used in LASIK eye surgery? 1 i) Infrared rays ii)Ultraviolet rays iii) Radio waves (iv)Gamma rays 9 A rectangular, a square, a circular and an elliptical loop, all in the (x-y) plane, are moving 1 out of a uniform magnetic field with a constant velocity 𝑣⃗⃗ = v𝚤̂.The magnetic field is directed along the negative z-axis direction. The induced emf, during the passage of these loops, out of the field region, will not remain constant for (i) any of the four loops ii) the circular and elliptical loops iii) the rectangular, circular and elliptical loops iv) only the elliptical loops 10 The angle of minimum deviation measured with a prism is 30° and the angle of prism is 1 60°. The refractive index of prism material is (i)√2 (ii) 2 (iii) 3/2 (iv) 4/3 11 The energy of the innermost electron orbit of a hydrogen atom is -13.6eV. The potential 1 energy of the n =2 orbit is (i) -6.8eV (ii)- 27.2ev (iii)- 3.4eV (iv) -24.8eV 12 What is the radius of Co27 nucleus if R0=1.2 fm? 1 (i)2.4fm (ii)3.6fm (iii)4.8fm (iv)32.4fm 13 Two statements are given-one labelled Assertion (A) and the other labelled Reason (R). 1 Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below. a) Both A and R are true and R is the correct explanation of A b) Both A and R are true and R is NOT the correct explanation of A c) A is true but R is false d) A is false and R is also false ASSERTION(A): The self inductance of a solenoid increases by inserting a soft iron core inside it. REASON: The inductive reactance of an inductor is zero for D.C. 14 Two statements are given-one labelled Assertion (A) and the other labelled Reason (R). 1 Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below. a)Both A and R are true and R is the correct explanation of A 19 | P a g e  b)Both A and R are true and R is NOT the correct explanation of A c)A is true but R is false d)A is false and R is also false ASSERTION(A): The electrical conductivity of a N-type semiconductor is more than P-type semiconductor. REASON: Doping always increases the number of electrons in thesemiconductor. 15 Two statements are given-one labelled Assertion (A) and the other labelled Reason (R). 1 Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below. a) Both A and R are true and R is the correct explanation of A b) Both A and R are true and R is NOT the correct explanation of A c) A is true but R is false d) A is false and R is also false ASSERTION: In an interference pattern if the blue color light is replaced with red color light the fringe width increases. REASON: Fringe width is proportional to (d/D). 16 Two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the 1 correct answer to these questions from the codes (a), (b), (c) and (d) as given below. a) Both A and R are true and R is the correct explanation of A b Both A and R are true and R is NOT the correct explanation of A c) A is true but R is false d) A is false and R is also false Assertion(A) :On increasing the intensity of incident light the maximum kinetic energy of the emitted electrons increase. Reason(R) : The energy of electrons emitted from inside the metal surface, is lost in collision with the other atoms in the metal. SECTION-B 17 The magnetic component of a wave of light is Bx = (4.0 × 10-6 T) sin [(1.57 × 107 m-1) y + wt]. 2 Find the intensity of light? 18 A galvanometer coil has a resistance of 12Ω and the meter shows full scale deflection for a 2 current of 3mA. How will you convert the meter into a voltmeter of range 0-18 V.? 19 What is the nuclear radius of 125Fe ,if that of 27 Al is 3.6 fermi?. 2 OR The short wavelength limit for the Lyman series of the hydrogen spectrum is 913.4 A0. Calculate the short wavelength limit for the Paschen series of the hydrogen spectrum. 20 A biconvex lens made of a transparent material of refractive index 1.25is immersed in water of 2 refractive index 1.3. Will the lens behave as a converging or a diverging lens or a plane glass plate? Justify your answer. 20 | P a g e 21 The figure shows a piece of pure semiconductor S in series with a variable resistor R and a 2 source of constant voltage V. Should the valueof R be increased or decreased to keep the reading of the ammeter constant, when semiconductor S is heated? Justify your answer OR Distinguish between N-type and P-type semiconductor? Why the conductivity of N-type semiconductor is more than P-type semiconductor? SECTION-C 22 The intensity, at the central maxima(O) in a Young’s double slit set up is I0.If the distance OP 3 equals one third of the fringe width of the pattern, show that the intensity, at point P., would equal I0/4 23 A wire of uniform cross-section and resistance 4 ohm is bent in the shape of square ABCD. 3 Point A is connected to a point P on DC by a wire AP of resistance 1 ohm. When a potential difference is applied between A and C, the points B and P are seen to be at the same potential. What is the resistance of the part DP? 24 Calculate the magnetic field at any point on the axial line of a circular current carrying coil 3 having no of turns N and radius R? 25 The magnetic field through a circular loop of wire, 12cm2 in area and 6 Ω resistance, changes 3 with time as shown in the figure. The magnetic field is perpendicular to the plane of the loop. Calculate the current induced in the loop between 0 to 2 second and 2 to 4 second? 21 | P a g e 26 An a.c. source generating a voltage ε = ε0 sin ωt is connected to a capacitor of capacitance C. 3 Find the expression for the current I flowingthrough it. Plot a graph of ε and I versus ωt to show that the current is ahead of the voltage by a phase angle π/2. OR An ac voltage V = V0 sin ωt is applied across a pure inductor of inductance L. Find an expression for the current i, flowing in the circuit and show mathematically that the current flowing through it lags behind the applied voltage by a phase angle of π/2. Also draw graphs of V and i versus ωt for the circuit. 27 15 Radiation of frequency 10 Hz is incident on three photosensitivesurfaces A, B and C. 3 Following observations are recorded: Surface A: no photoemission occurs Surface B: photoemission occurs but the photoelectrons have zero kinetic energy. Surface C: photo emission occurs and photoelectrons have some kinetic energy. Using Einstein’s photo-electric equation, explain the three observations. OR The graph shows the variation of photocurrent for aphotosensitive metal (a) What does X and A on the horizontal axis represent? (b) Draw this graph for three different values of frequencies of incident radiation ʋ1, ʋ 2 and ʋ 3 (ʋ 3>ʋ 2>ʋ1) for the same intensity. Draw this graph for three different values of intensities of incidentradiation I1, I2 and I3 given (I3> I2>I1) having the same frequency. 28 The ground state energy of hydrogen atom is -13.6 eV. The photon emitted during the transition 3 of electron from n=3 to n=1 state, is incident on a photosensitive material of unknown work function.The photoelectrons are emitted from the material with the maximum kineticenergy of 9eV.Calculate the threshold wavelength of the material used. SECTION-D 29 In 1678, a Dutch scientist, Christian Huygens propounded wave theory of light. According to 4 him, wave theory introduced the concept of wave front. Light travels in the form of waves. A wave front is the locus of points having the same phase of oscillations. A wavelet is the point of disturbance due to propagation of light. i)Why light rays bend around the sharp corners of an obstacle? a)Due to Diffraction b)Due to dispersion c)Due to interference d)Due to Refraction ii)If the intensities of each slit is Io in interference then intensity of maximum is a)2 Io b)Io c)4Io d)None of these iii)In coherent sources necessary to produce a sustained interference pattern which of the following may be different? a) Intensity b)Amplitude c)Frequency d)Initial Phase OR If the ratio of the amplitudes of two sources is 4:9 then what will be the ratio of intensity of maximum to minimum? 22 | P a g e  a)25:1 b)1:25 c)169:25 d)1:1 iv)If the intensity of central maximum in YDSE is IO ,then the intensity at a point having path difference λ/3 is a)IO b)IO/2 c)2 IO d)2 IO/3 30 A rectifier is an electrical device that converts alternating current (ac), which periodically 4 reverses direction, to direct current (dc), which flows in only one direction. The reverse operation is performed by the inverter. The process is known as rectification. From V-I characteristics of a junction diode we see that it allows current to pass only when it is forward biased. So, if an alternating voltage is applied across a diode the current flows only in that part of the cycle when the diode is forward biased. This property of diode is used to rectify alternating voltage and the circuit used for this purpose is said to be rectifier. A crystal diode having internal resistance Rf = 20Ω is used for half-wave rectification. If the applied voltage is given by v = 50 sin wt and load resistance RL = 80Ω i) What will be the peak value of current? a)0.5amp b)2amp c)4amp d)1amp ii)What is the mean value of D.C over the complete cycle? a)0.5/π amp b)1/ π amp c)2/ π amp d)Zero iii)What is the D.C power out put across the load resistance? a)10 wt b)20wt c)30wt d)40wt iv)If the value of w=120π then what will be the frequency of output D.C.in the full wave rectifier a)60Hz b)100Hz c)120Hz d)200Hz SECTION-E 31 i) A thin lens, having two surfaces of radii of curvature R1 and R2,made from a material of 5 refractive index µ2 is kept in a medium of refractive index µ1. Derive the Lens maker’s formula using this setup. (ii) A convex lens is placed over a plane mirror. A pin is now positioned so that there is no parallax between the pin and its image formed by this lens-mirror combination. How can this observation be used to find the focal length of the convex lens? Give appropriate reasons in support of your answer. OR i) Define critical angle and derive its relation with refractive index of a medium? ii) A point source is kept at a depth d from the surface of a liquid of refractive index μ. Then find out the area on the surface of liquid through which the light rays from the source will move out? iii)Draw the angle of deviation vs angle of incidence graph in case of a light ray passing through a prism ? 32 (a) State Gauss’s law in electrostatics. With help of suitable diagram show that outward flux due 5 to a point charge Q, in vacuum within Gaussian surface, is independent of its size and shape. b)In the figure there are three infinite long thin sheets having surface charge density +2σ, -2σ and +σ respectively. Give the magnitude and direction of electric field at a point to the left of sheet of charge density +2σ and to the right of sheet of charge density +σ. 23 | P a g e  OR A thin conducting spherical shell of radius R has charge Q spread uniformly over its surface. Using Gauss’s theorem, derive an expression for the electric field at a point outside the shell, on the surface of the shell and inside the shell. Draw a graph of electric field E(r) with distance r from the centre of the shell for 0 ≤ r ≤∞. 33 Define the term Resistivity of a material? Write its SI unit and obtain its dimension? Derive the 5 expression for resistivity of a material in terms of relaxation time of the electrons? Why the resistivity of conductors increase on increasing the temperature? OR (a) State the two Kirchhoff’s rules used in the analysis of electric circuits and explain them. (b) Derive the equation of the balanced state in a Wheatstone bridge using Kirchhoff’s laws. 24 | P a g e  DAV PUBLIC SCHOOLS, ODISHA ZONE-D SAMPLE PAPER -4/5 (2023-24) CLASS- XII SUB : PHYSICS THEORY(042) Time Allowed: 3 Hours Maximum Marks : 70 General Instructions : (1) There are 33 questions in all. All questions are compulsory. (2) This question paper has five sections: Section A, Section B, Section C, Section D and Section E. (3) All the sections are compulsory. (4) Section A contains sixteen questions, twelve MCQ and four Assertion Reasoning based of 1 mark each, Section B contains five questions of two marks each, Section C contains seven questions of three marks each, Section D contains two case study- based questions of four marks each and Section E contains three long answer questions of five marks each. (5) There is no overall choice. However, an internal choice has been provided in one question in Section B, two questions in Section C, one question in each CBQ in Section D and all three questions in Section E. You have to attempt only one of the choices in such questions. (6) Use of calculators is not allowed. (7) You may use the following values of physical constants where ever necessary i. c = 3 x 108 m/s ii. me = 9.1 x10-31 kg iii. e = 1.6 x 10-19 C iv. µ0 = 4π x 10-7 Tm𝐴 −1 v. h = 6.63 x10-34 Js vi. ε0 = 8.854 x10-12 𝐶 2𝑁 −1𝑚−2 vii. Avogadro’s number = 6.023 X 1023 per gram mole SECTION A Q MARK No S 1 Two charges of magnitudes -2Q and + Q are located at point (a, 0) and (4a, 0) respectively. 1 The electric flux due to these charges through a sphere of radius ‘3a’ with its centre at the origin is (a) -2Q/ε0 (b) -3Q/ε0 (c) -Q/ε0 (d) Q/ε0 2 A hallow metal sphere of radius 5 cm is charged such that the potential on it surface is 10V. 1 The potential at a distance 2.5 cm from the centre of the sphere is (a) 2V (b) 10V (c)5 V (d) 0 V 25 | P a g e 3 Two copper wires of lengths L and 2L have radii r and 2r respectively. What is the ratio of 1 their specific resistances? (a) 1 : 2 (b) 2 : 1 (c) 1 : 1 (d) 1 : 3 4 Two concentric and coplanar circular loops P and Q have their radii in the ratio 2:3. Loop Q 1 carries a current 9 A in the anticlockwise direction. For the magnetic field to be zero at the common centre, loop P must carry (a) 3A in clockwise direction (b) 9A in clockwise direction (c) 6 A in anti-clockwise direction (d) 6 A in the clockwise direction. 5 If the magnetizing field on a ferromagnetic material is increased, its permeability 1 (i) decreases (ii) increases (iii) remains unchanged (iv) first decreases and then increases 6 Current in a circuit steadily decreases from 2.0 A to 0.0 A in 10 ms. If an average e.m.f. of 1 200V is induced, then the self-inductance of the circuit is (a) 1H (b) 2H (c)5 H (d) 0 H 7 The quality factor of a series LCR circuit with L = 2 H, C= 2 μF and R = 10 Ω is 1 (a) 1 (b) 20 (c)50 (d) 100 8 Which of the following statement is NOT true about the properties of electromagnetic 1 waves? (a) These waves do not require any material medium for their propagation (b) Both electric and magnetic field vectors attain the maxima and minima at the same time (c) The energy in electromagnetic wave is divided equally between electric and magnetic fields (d) Both electric and magnetic field vectors are parallel to each other 9 Two coherent monochromatic light beams of intensities I and 4I superpose each other. The 1 ratio of maximum and minimum intensities in the resulting beam is (a) 9:1 (b) 1:9 (c)1:1 (d) 1:4 10 The stopping potential of a photocell, in which electrons with a maximum kinetic energy of 1 6 eV are emitted is (a) 6V (b) 12V (c)10V (d) 18V 11 Two nuclei have mass numbers in the ratio 2 : 5. The ratio of their nuclear densities is 1 (a) 2:5 (b) 5:2 (c)1:1 (d) 1:8 12 In an extrinsic semiconductor, the number density of holes is 4 x 1020 m-3. If the number 1 density of intrinsic carriers is 1.2 x 1015 m-3. The number density of electrons in it is (a) 1.8 x 109 m-3 (b) 2.4 x 1010 m-3 (c) 3.6 x 109 m-3 (d) 3.2 x 1010 m-3 For Questions 13 to 16, two statements are given –one labelled Assertion (A) and other 1 labelled Reason (R). Select the correct answer to these questions from the options as given below. a) If both Assertion and Reason are true and Reason is correct explanation of Assertion. b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion. c) If Assertion is true but Reason is false. d) If both Assertion and Reason are false. 13 Assertion : A negative charge in an electric field moves along the direction of electric field. 1 Reason : On a negative charge a force acts in the direction of the electric field. 14 Assertion(A): Assertion: The temperature coefficient of resistance is always positive for 1 metallic and alloy conductor. 26 | P a g e  Reason: On increasing the temperature, the resistance of metals and alloys increases 15 Assertion : The phase difference between any two points on a wave front is zero. 1 Reason : All points on a wavefront are oscillate in the same phase. 16 Assertion : If the temperature of a semiconductor is increased then its resistance decreases. 1 Reason : The energy gap between conduction band and valence band is very small. SECTION- B 17 (i) A uniform magnetic field gets modified as shown below when two specimens X and 2 Y are placed in it. Identify whether specimens X and Y are diamagnetic, paramagnetic or ferromagnetic. (ii) How is the magnetic susceptibility of specimen X different from that of specimen Y? 18 A metallic rod of 1 m length is rotated with a frequency of 50 rev/s, with one end hinged 2 at the centre and the other end at the circumference of a circular metallic ring of radius 1 m, about an axis passing through the centre and perpendicular to the plane of the ring). A constant and uniform magnetic field of 1 T parallel to the axis is present everywhere. What is the emf between the centre and the metallic ring? 19 Figure shows a ray of light passing through a prism. If the refracted ray QR is parallel to 2 the base BC, show that (i) r1 = r2 = A/2, (ii) angle of minimum deviation, Dm = 2i – A 20 The energy of the electron in the ground state of hydrogen atom is – 13.6 eV. 2 (i) What does the negative sign signify? (ii) How much energy is required to take an electron in this atom from the ground state to the first excited state? 21 Draw energy band diagrams of an n-type and p-type semiconductor at temperature T > 0 2 K. Mark the donor and acceptor energy levels with their energies. OR 27 | P a g e  What is forward biased and reverse biased of pn junction diode. Draw a typical V-I characteristics in forward biased and reverse biased of pn junction diode SECTION- C 22 Three concentric metallic shells A, B and C of radii a, b and c (a < b < c) have surface charge 3 densities +σ, - σ and + σ respectively as shown in the figure. If shells A and C are at the same potential, then obtain the relation between the radii a, b and c 23 Define the term ‘drift velocity’ of charge carriers in a conductor. Obtain the expression for 3 the current density in terms of relaxation time. 24 A proton and an alpha particle are accelerated through the same potential. Which one of the 3 two has (i) greater value of de-Broglie wavelength associated with it, and (ii) less kinetic energy? Justify your answers. 25 Find the position of the image formed by the lens combination given in the Fig. 3 OR (i) If f = 0.5 m for a glass lens, what is the power of the lens? (ii) The radii of curvature of the faces of a double convex lens are 10 cm and 15 cm. Its focal length is 12 cm. What is the refractive index of glass? (iii) A convex lens has 20 cm focal length in air. What is focal length in water? (Refractive index of air-water = 1.33, refractive index for air-glass = 1.5. 26 What is the effect on the interference fringes in a Young’s double-slit experiment due to each 3 of the following operations: (a) the screen is moved away from the plane of the slits; (b) the (monochromatic) source is replaced by another (monochromatic) source of shorter wavelength; (c) the separation between the two slits is increased. 28 | P a g e  27 Write any two distinguishing features between conductors, semiconductors and insulators on 3 the basis of energy band diagrams. OR Explain, with the help of a circuit diagram, the working of a p-n junction diode as a half- wave rectifier. Draw the input and output waveforms 28 The magnetic field in a plane electromagnetic wave is given by 3 By = (2 × 10–7) T sin (0.5×103x+1.5×1011t). (a) What is the wavelength of the wave? (b) Write an expression for the electric field. (c) Draw a diagram showing the propagation of an electromagnetic wave along z-direction indicating clearly the directions of oscillating electric and magnetic fields associated with it. SECTION- D 29 Case Study Based Questions 4 Moving coil galvanometer operates on Permanent Magnet Moving Coil (PMMC) mechanism and was designed by the scientist D’arsonval. Moving coil galvanometers are of two types: (i) Suspended coil (ii) Pivoted coil type or tangent galvanometer. Its working is based on the fact that when a current carrying coil is placed in a magnetic field, it experiences a torque. This torque tends to rotate the coil about its axis of suspension in such a way that the magnetic flux passing through the coil is maximum. (i)A moving coil galvanometer is an instrument which (a) is used to measure emf (b) is used to measure potential difference (c) is used to measure resistance (d) is a deflection instrument which gives a deflection when a current flows through its coil (ii)To make the field radial in a moving coil galvanometer. (a) number of turns of coil is kept small (b) magnet is taken in the form of horse-shoe (c) poles are of very strong magnets (d) poles are cylindrically cut (iii)The deflection in a moving coil galvanometer is (a) directly proportional to torsional constant of spring (b) directly proportional to the number of turns in the coil 29 | P a g e  (c) inversely proportional to the area of the coil (d) inversely proportional to the current in the coil (iv)In a moving coil galvanometer, having a coil of N-turns of area A and carrying current I is placed in a radial field of strength B. The torque acting on the coil is (a) NA2B2I (b) NABI2 (c) N2ABI (d) NABI OR (iv)To increase the current sensitivity of a moving coil galvanometer, we should decrease (a) strength of magnet (b) torsional constant of spring (c) number of turns in coil (d) area of coil 30 Read the following paragraph and answer the questions that follow. 4 Types of Lenses and their combination A convex or converging lens is thicker at the centre than at the edges. It converges a beam of light on refraction through it. It has a real focus. Convex lens is of three types: Double convex lens, Plano convex lens and Concavo-convex lens. Concave lens is thinner at the centre than at the edges. It diverges a beam of light on refraction through it. It has a virtual focus. Concave lenses are of three types: Double concave lens, Plano concave lens and Convexo-concave lens. When two thin lenses of focal lengths f1 and f2 are placed in contact with each other along their common principal axis, then the two lens system is regarded as a single lens of focal length f and 1/𝑓=1/f1 +1/f2 If several thin lenses of focal length f1, f2,.... fn are placed in contact, then the effective focal length of the combination is given by and in terms of power, we can write P = P1 + P2 +.... + Pn The value of focal length and power of a lens must be used with proper sign consideration. i. Two thin lenses are kept coaxially in contact with each other and the focal length of the 30 | P a g e  combination is 80 cm. If the focal length of one lens is 20 cm, the focal length of the other would be (a) -26.7cm (b) 60cm (c) 80cm (d) 30cm ii. A spherical air bubble is embedded in a piece of glass. For a ray of light passing through the bubble, it behaves like a (a) converging lens (b) diverging lens (c) mirror (d) thin plane sheet of glass iii. Lens generally used in magnifying glass is (a) single concave lens (b) single convex lens (c) combination of convex lens of lower power and concave lens of lower focal length (d) Planoconcave lens iv. The magnification of an image by a convex lens is positive only when the object is placed (a) at its focus F (b) between F and 2F (c) at 2F (d) between F and optical centre OR A convex lens of 20 cm focal length forms a real image which is three times magnified. The distance of the object from the lens is (a) 13.33 cm (b) 14 cm (c) 26.66 cm (d) 25 cm SECTION- E 31 (a) Deduce the expression for the torque acting on a dipole of dipole 5 moment p in the presence of a uniform electric field E. (b) Consider two hollow concentric spheres, S1 and S2, enclosing charges 2Q and 4Q respectively as shown in the figure. (i) Find out the ratio of the electric flux through them. (ii) How will the electric flux through the sphere S1 change if a medium of dielectric constant ‘εr’ is introduced in the space inside S1 in place of air? Deduce the necessary expression. OR (a)(i) Obtain the expression for the electric field intensity due to a uniformly charged spherical shell of radius R at a point distant r from the centre of the shell outside it. (ii) Draw a graph showing the variation of electric field intensity E with r, for r > R and r < 31 | P a g e  R. (b)Three charges –q, Q and –q are placed at equal distances on a straight line. If the potential energy of the system of these charges is zero, then what is the ratio Q:q? 32 (a) Using Bohr’s postulates, derive the expression for the total energy of the electron in the 5 stationary states of the hydrogen atom. (b) Using Rydberg formula, calculate the wavelengths of the spectral lines of the first member of the Lyman series and of the Balmer series. OR (a)Draw a plot showing the variation of binding energy per nucleon versus the mass number A. Explain with the help of this plot the release of energy in the processes of nuclear fission and fusion. (b) Plot a graph showing the variation of potential energy of a pair of nucleons as a function of their separation. Write two important conclusions which you can draw regarding the nature of nuclear forces. 33 (a) A pure inductor of inductance L is connected to an ac source having voltage V =V0 sin 5 ωt. Derive the expression for the instantaneous current and its phase relationship to the applied voltage. (b) When an alternating voltage of 220V is applied across a device X, a current of 0.25A flows which lags behind the applied voltage in phase by π/2 radian. If the same voltage is applied across another device Y, the same current flows but now it is in phase with the applied voltage. (i) Name the devices X and Y. (ii) Calculate the current flowing in the circuit when the same voltage is applied across the series combination of X and Y. OR (a)A series LCR circuit is connected to an ac source. Using the phasor diagram, derive the expression for the impedance of the circuit. (b) A circuit is set up by connecting inductance L = 100 mH, resistor R = 100 Ω and a capacitor of reactance 200 Ω in series. An alternating emf of 150 √2 V, 500/π Hz is applied across this series combination. Calculate the power dissipated in the resistor. 32 | P a g e  DAV PUBLIC SCHOOLS, ODISHA ZONE-D SAMPLE PAPER -5/5 [2023-24] CLASS-XII SUBJECT: PHYSICS Time Allowed: 3 Hours Maximum Marks:70 General Instructions: 1. There are 33 questions in all. All questions are compulsory. 2. This question paper has five sections: Section A, Section B, Section C, Section D and Section E. 3. All the sections are compulsory. 4. Section A contains sixteen questions, twelve MCQ and four Assertion Reasoning based of 1 mark each, Section B contains five questions of two marks each, Section C contains seven questions of three marks each, Section D contains two case study based questions of four marks each and Section E contains three long answer questions of five marks each. 5. There is no overall choice. However, an internal choice has been provided in one question in Section B, one question in Section C, one question in each CBQ in Section D and all three questions in Section E. You have to attempt only one of the choices in such questions. 6. Use of calculators is not allowed. 7. You may use the following values of physical constants where ever necessary i. c = 3 × 108 ii. me = 9.1 ×10-31 kg iii. e = 1.6 × 10-19 C iv. µ0 = 4π × 10-7 TmA-1 v. h = 6.63 × 10-34 Js vi. ε0 = 8.854 ×10-12 C2 N-1 m-2 vii. Avogadro’s number = 6.023 × 1023 g/mol Section-A Answer all the questions. 1. A parallel plate capacitor is made of two dielectric blocks in series. One of the blocks has thickness d1 and dielectric constant k1 and the other has thickness d2 and dielectric constant k2 as shown in figure. This arrangement can be thought as a dielectric slab of thickness d (= d1+d2) and effective dielectric constant k. The k is 𝑘1 𝑑1 +𝑘2 𝑑2 (a) 𝑑1 +𝑑2 1 𝑘1 𝑑1 +𝑘2 𝑑2 (b) 𝑘1 +𝑘2 𝑘1 𝑘2 (𝑑1 +𝑑2 ) (c) 𝑘1 𝑑1 +𝑘2 𝑑2 2𝑘1 𝑘2 (d) 𝑘 1 +𝑘2 2 A parallel plate capacitor with air between the plates has a capacitance of 8 pF. The 1 separation between the plates is now reduced half and the space between them is filled with 33 | P a g e  a medium of dielectric constant 5. Calculate the value of capacitance of the capacitor in second case. (a) 8pF (b) 10pF (c) 80pF (d) 100pF 3 Two batteries of emf 𝜀1 and 𝜀2 (𝜀1 > 𝜀2 ) and internal resistances 𝑟1 and 𝑟2 respectively are connected in parallel as shown in Figure. (a) The equivalent emf 𝜀𝑒𝑞 of the two cells is between 𝜀1 and 𝜀2 , i.e., 𝜀1 < 𝜀𝑒𝑞 < 𝜀2. 1 (b) The equivalent emf 𝜀𝑒𝑞 is smaller than 𝜀1. (c) The 𝜀𝑒𝑞 is given by 𝜀𝑒𝑞 = 𝜀1 + 𝜀2 always. (d) 𝜀𝑒𝑞 is independent of internal resistances 𝑟1 and 𝑟2. 4 An emf is produced in a coil, which is not connected to an external voltage source. This can be due to (i) the coil being in a time varying magnetic field. (ii) the coil moving in a time varying magnetic field. (iii) the coil moving in a constant magnetic field. (iv) the coil is stationary in external spatially varying magnetic field, which does not 1 change with time. (a) (i) and (ii) (b) (i),(ii) and (iii) (c) (i),(ii) and (iv) (d) (ii) and (iv) 5 In the following figure, the magnet is moved towards the coil with a speed v and induced emf is e. If magnet and coil recede away from one another each moving with speed v, the induced emf in the coil will be (a) e 1 (b) 2e (c)e/2 (d) 4e 6 A rectangular coil ABCD is rotated anticlockwise with a uniform angular velocity about the axis shown in diagram below. The axis of rotation of the coil as well as the magnetic field B are horizontal. The induced emf. in the coil would be maximum when (a) The plane of the coil is horizontal (b) The plane of the coil makes an angle of 45° with the magnetic 1 field (c) The plane of the coil is at right angles to the magnetic field (d) The plane of the coil makes an angle of 30° with the magnetic field 7 Which of the following is used to investigate the structure of solids? (a) Gamma Rays 1 (b) Infrared Rays (c) X-Rays 34 | P a g e  (d) Cosmic Rays 8 Which of the following figures represent the variation of particle momentum and the associated de-Broglie wavelength? 1 27 125 9 If radius of the 13𝐴𝑙 nucleus is taken to be 𝑅𝐴𝑙 , then the radius of 53𝑇𝑒 nucleus is nearly 1 3 13 53 5 (a) 5 𝑅𝐴𝑙 (𝑏)( )1/3 𝑅𝐴𝑙 (c) (13)1/3 𝑅𝐴𝑙 (d) 3 𝑅𝐴𝑙 53 10 One requires 11 eV of energy to dissociate a carbon monoxide molecule into carbon and oxygen atoms. The minimum frequency of the appropriate electromagnetic radiation to achieve the dissociation lies in (a) visible region 1 (b) infrared region (c) ultraviolet region (d) microwave region 11 You are given four sources of light each one providing a light of a single colour – red, blue, green and yellow. Suppose the angle of refraction for a beam of yellow light corresponding to a particular angle of incidence at the interface of two media is 90°. Which of the following statements is correct if the source of yellow light is replaced with that of other lights without changing the angle of incidence? (a) The beam of red light would undergo total internal reflection. 1 (b) The beam of red light would bend towards normal while it gets refracted through the second medium. (c) The beam of blue light would undergo total internal reflection. (d) The beam of green light would bend away from the normal as it gets refracted through the second medium. 12 Consider sunlight incident on a pinhole of width 103 Å. The image of the pinhole seen on a screen shall be (a) a sharp white ring. 1 (b) same as a geometrical image (c) a diffused central spot, white in colour. (d) diffused coloured region around a sharp central white spot. Directions: These questions consist of two statements, each printed as Assertion and Reason. While answering these questions, you are required to choose any one of the following four responses. (a) If both Assertion and Reason are correct and the Reason is a correct explanation of the Assertion. (b) If both Assertion and Reason are correct but Reason is not a correct explanation of the Assertion. (c) If the Assertion is correct but Reason is incorrect. 35 | P a g e  (d) If both the Assertion and Reason are incorrect. 13 Assertion (A): If objective and eye lenses of a microscope are interchanged, then it can work as telescope. 1 Reason(R): The objective lens of telescope has small focal length 14 Assertion(A) : Induced emf will always occur whenever there is change in magnetic flux. 1 Reason(R) : Current always induces whenever there is change in magnetic flux. 15 Assertion (A): When ultraviolet light is incident on a photocell, its stopping potential is 𝑉0 and the maximum kinetic energy of the photoelectrons is 𝐾𝑚𝑎𝑥. When the ultraviolet light is replaced by X-rays, both 𝑉0 and 𝐾𝑚𝑎𝑥 increase. 1 Reason (R): Photoelectrons are emitted with speeds ranging from zero to a maximum value because of the range of frequencies present in the incident light. 16 Assertion (A): In Lyman series, the ratio of minimum and maximum wavelength is 3/4. Reason (R): Lyman series constitute spectral lines corresponding to transition from higher 1 energy to ground state of hydrogen atom. Section-B 17 Define the term ‘intensity of radiation’ in photon picture of light. Ultraviolet light of wavelength 2270 Å from 100 W mercury source irradiates a photo cell made of a given metal. If the stopping potential is –1.3 V, estimate the work function of the metal. How 2 would the photocell respond to a high intensity (~ 105 W𝑚−2) red light of wavelength 6300 Å produced by a laser? 18 Use Kirchhoff’s laws to determine the value of current I1 in the given electrical circuit. 2 (OR) Two metallic wires, 𝑃1 and P2 of the same material and same length but different cross- sectional areas, A1 and A2 are joined together and connected to a source of emf. Find the ratio of the drift velocities of free electrons in the two wires when they are connected (i) in series, and (ii) in parallel. 19 In a plane electromagnetic wave, the electric field oscillates with a frequency of 2 × 1010 𝑠 −1 and an amplitude of 40 𝑉𝑚−1. 2 (i) What is the wavelength of the wave? (ii) What is the energy density due to electric field? 20 An equilateral glass prism has a refractive index 1.6 in air. Calculate the angle of minimum 4√2 2 deviation of the prism, when kept in a medium of refractive index 5. 21 (a) Carbon and silicon have the same lattice structure. Then why is carbon an insulator but silicon a semiconductor? (b) In the following diagram ‘S’ is a semiconductor. Would you increase or decrease the 2 value of R to keep the reading of the ammeter A constant when S is heated? Give reason for your answer. 36 | P a g e  Section-C 22 (i) Find equivalent capacitance between A and B in the combination given below. Each capacitor is of 2 µF capacitance. 3 (ii) If a dc source of 7V is connected across AB, how much charge is drawn from the source and what is the energy stored in the network. 23 (a) An iron ring of relative permeability 𝜇𝑟 has windings of insulated copper wire of n turns per metre. When the current in the windings is I, find the expression for the magnetic field in the ring. (b) The susceptibility of a magnetic material is 0.9853. Identify the type of 3 magnetic material. Draw the modification of the field pattern on keeping a piece of this material in a uniform magnetic field. 24 (a)A wire of resistance R, length l and area of cross-section A, is cut into two parts, having their lengths in the ratio 1 : 2. The shorter wire is now stretched till its length becomes equal to that of the longer wire. If they are now connected in parallel, find the net resistance 3 of the combination. (b) Why are alloys used for making standard resistance coils? 25 Obtain the first Bohr’s radius and the ground state energy of a muonic hydrogen atom, i.e., an atom where the electron is replaced by a negatively charged muon (𝜇 − ) of mass about 207 𝑚𝑒 that orbits around a proton. (Given for hydrogen atom, radius of first orbit and 3 ground state energy are 0.53 × 10−10 m and – 13.6 eV respectively) 26 In the following nuclear reaction, calculate the energy released in MeV: Given: 21𝐻 + 31𝐻 → 42𝐻𝑒 + 𝑛 𝑚( 21𝐻 ) = 2.014102 𝑢 𝑚( 31𝐻 ) = 3.016049 𝑢 𝑚( 42𝐻𝑒) = 4.002603 𝑢 𝑚𝑛 = 1.008665 𝑢 (OR) 3 (a)A heavy nucleus P of mass number 240 and binding energy 7.6 MeV per nucleon splits in to two nuclei Q and R of mass numbers 110, 130 and binding energy per nucleon 8.5 MeV and 8.4 MeV, respectively. Calculate the energy released in the fission. (b) Draw a plot showing the variation of binding energy per nucleon versus the mass number (A).Briefly explain its importance. 37 | P a g e 27 How is a wavefront defined? Using Huygen’s constructions draw a figure showing the propagation of a plane wave refracting at a plane surface separating two media. Hence 3 verify Snell’s law of refraction. 28 A convex lens made up of glass of refractive index 1.5 is dipped, in turn, in (i) a medium of refractive index 1.65, (ii) a medium of refractive index 1.33. 3 (a) Will it behave as a converging or a diverging lens in the two cases? (b) How will its focal length change in the two media? Section-D Case Study Based Questions 29 Read the following paragraph and answer the questions that follow:- Moving coil galvanometer operates on Permanent Magnet Moving Coil (PMMC) mechanism and was designed by the scientist D’arsonval. Moving coil galvanometers are of two types: (i) Suspended coil (ii) Pivoted coil type or tangent galvanometer. Its working is based on the fact that when a current carrying coil is placed in a magnetic field, it experiences a torque. This torque tends to rotate the coil about its axis of suspension in such a way that the magnetic flux passing through the coil is maximum. (i)A moving coil galvanometer is an instrument which (a) is used to measure emf (b) is used to measure potential difference (c) is used to measure resistance (d) is a deflection instrument which gives a deflection when a current flows through its coil (ii) To make the field radial in a moving coil galvanometer. (a) number of turns of coil is kept small 4 (b) magnet is taken in the form of horse-shoe (c) poles are of very strong magnets (d) poles are cylindrically cut (iii) The deflection in a moving coil galvanometer is (a) directly proportional to torsional constant of spring (b) directly proportional to the number of turns in the coil (c) inversely proportional to the area of the coil (d) inversely proportional to the current in the coil (iv) In a moving coil galvanometer, having a coil of N-turns of area A and carrying current I is placed in a radial field of strength B. The torque acting on the coil is (a) 𝑁𝐴2 𝐵 2 𝐼 (b) 𝑁𝐴B𝐼 2 (c) 𝑁 2 𝐴𝐵𝐼 (d) NABI (OR) 38 | P a g e  To increase the current sensitivity of a moving coil galvanometer, we should decrease (a) strength of magnet (b) torsional constant of spring (c) number of turns in coil (d) area of coil 30 Interference (Young’s Double slit experiment) Young’s double slit experiment uses two coherent sources of light placed at a small distance apart. Usually, only a few orders of magnitude greater than the wavelength of light are used. Young’s double slit experiment helped in understanding the wave theory of light, which is explained with the help of a diagram. As shown, a screen or photodetector is placed at a large distance, ‘D’, away from the slits. (i) What is the path difference between the two light waves coming from coherent sources, which produces 3rd maxima. (a)  (b) 2 (c) 3 (d) 0 (ii) In Young’s double slit experiment, if the separation between coherent sources is halved and the distance of the screen from the coherent sources is doubled, then the fringe width becomes 4 (a) double (b) half (c) four times (d) one-fourth (iii) The ratio of the widths of two slits in Young’s double slit experiment is 4 : 1. Evaluate the ratio of intensities at maxima and minima in the interference pattern. (a) 1:1 (b) 1:4 (c) 3:1 (d) 9:1 (iv) In a Young’s double slit experiment, the separation between the slits is 0.1 mm, the wavelength of light used is 600 nm and the interference pattern is observed on a screen1m away. Find the separation between bright fringes. (a) 6.6 mm (b) 6.0 mm (c) 6 m (d) 60cm (OR) In a Young’ double slit experiment if there is no initial phase difference between the light from the two slits, a point on the screen corresponding to the fifth minimum has path difference. 𝜆 (a) 5 2 𝜆 (b) 102 𝜆 (c) 92 𝜆 (d) 112 39