Tiêu đề Class XII physics (7 years)- 48 pages (1).pdf ✅

Shiv Das PHYSICS – 2024 (Series: RQSP4/4)  293 Series: RQSP4/4 Q. P. Code No. 55/4/1 Roll No. Candidates must write the Q.P. Code on the title page of the answer-book. • Please check that this question paper contains 10 printed pages. • Please check that this question paper contains 33 questions. • Q.P. Code given on the right hand side of the question paper should be written on the title page of the answer-book by the candidate. • Please write down the serial number ofthe question in the answer-book before attempting it. • 15 minute time has been allotted to read this question paper. The question paper will be distributed at 10.15 a.m. From 10.15 a.m. to 10.30 a.m., the candidates will read the question paper only and will not write any answer on the answer-book during this period. PHYSICS (Theory) – XII CBSE – 2024 (SERIES: RQSP4/4) Time Allowed: 3 hours Maximum Marks: 70 GENERAL INSTRUCTIONS: Read the following instructions very carefully and follow them: (i) This question paper contains 33 questions. All questions are compulsory. (ii) Question paper is divided into FIVE sections—Section A, B, C, D and E. (iii) Section–A: Questions number 1 to 16 are Multiple Choice (MCQ) type questions. Each question carries 1 mark. (iv) Section–B: Questions number 17 to 21 are Very Short Answer type questions. Each question carries 2 marks. (v) Section–C: Questions number 22 to 28 are Short Answer type questions. Each question carries 3 marks. (vi) Section–D: Questions number 29 and 30 are Case study–based questions. Each question carries 4 marks. (vii) Section–E: Questions number 31 to 33 are Long Answer type questions. Each question carries 5 marks. (viii) There is no overall choice given in the question paper. However, an internal choice has been provided in few questions in all the Sections except Section–A. (ix) Kindly note that there is a separate question paper for Visually Impaired candidates. (x) Use of calculators is NOT allowed. You may use the following values of physical constants wherever necessary: c = 3 × 108 m/s ; h = 6.63 × 10–34 Js e = 1.6 × 10–19 C ; μ0 = 4π × 10–7 T m A–1 ε0 = 8.854 × 10–12 C2 N–1 m–2 ; 1 4 0 πε = 9 × 109 N m2 C–2 Mass of electron (me ) = 9.1 × 10–31 kg; Mass of neutron = 1.675 × 10–27 kg Mass of proton = 1.673 × 10–27 kg; Avogadro’s number = 6.023 × 1023 per gram mole Boltzmann constant = 1.38 × 10–23 JK–1
Shiv Das 294  Shivdas SENIOR SECONDARY SERIES (XII) Set-I : 55/4/1 Section-A 16×1=16 Q.1. Two charges +q each are kept ‘2a’ distance apart. A third charge –2q is placed midway between them. The potential energy of the system is— 1 (a) q a 2 0 8πε (b) — 6 8 2 0 q πε a (c) −7 8 2 0 q πε a (d) 9 8 2 0 q πε a Q.2. Two identical small conducting balls B1 and B2 are given –7 pC and + 4 pC charges respectively. They are brought in contact with a third identical ball B3 and then separated. If the final charge on each ball is –2 pC, the initial charge on B3 was 1 (a) –2 pC (b) –3 pC (c) –5 pC (d) –15 pC Q.3. The quantum nature of light explains the observations on photoelectric effect as— 1 (a) there is a minimum frequency of incident radiation below which no electrons are emitted. (b) the maximum kinetic energy of photoelectrons depends only on the frequency of incident radiation. (c) when the metal surface is illuminated, electrons are ejected from the surface after sometime. (d) the photoelectric current is independent of the intensity of incident radiation. Q.4. The radius (rn) of nth orbit in Bohr model of hydrogen atom varies with n as 1 (a) rn ∝ n (b) rn ∝ 1 n (c) rn ∝ n2 (d) rn ∝ 1 n2 Q.5. A straight wire is kept horizontally along east–west direction. If a steady current flows in wire from east to west, the magnetic field at a point above the wire will point towards 1 (a) East (b) West (c) North (d) South Q.6. The magnetic susceptibility for a diamagnetic material is 1 (a) small and negative (b) small and positive (c) large and negative (d) large and positive Q.7. A galvanometer of resistance 100 Ω is converted into an ammeter of range (0 – 1A) using a resistance of 0.1 Ω. The ammeter will show full scale deflection for a current of about 1 (a) 0.1 mA (b) 1 mA (c) 10 mA (d) 0.1 A Q.8. A circular loop A of radius R carries a current I. Another circular loop B of radius r = R 20 ( ) is placed concentrically in the plane of A. The magnetic flux linked with loop B is proportional to 1 (a) R (b) R (c) R 3 2 (d) R2 Q.9. Figure shows the variation of inductive reactance XL of two ideal inductors of inductance L1 and L2, with angular frequency ω. The value of L L 1 2 is 1 (a) 3 (b) 1 3 (c) 3 (d) 1 3 60o 30o XL L1 O ω L2
Shiv Das PHYSICS – 2024 (Series: RQSP4/4)  295 Q.10. The phase difference between electric field E → and magnetic field B → in an electromagnetic wave propagating along z–axis is— 1 (a) zero (b) π (c) p 2 (d) p 4 Q.11. A coil of N turns is placed in a magnetic field B → such that B → is perpendicular to the plane of the coil. B → changes with time as B = B0 cos 2p T( ) t where T is time period. The magnitude of emf induced in the coil will be maximum at 1 (a) t = nT 8 (b) t = nT 4 (c) t = nT 2 (d) t = nT Here, n = 1, 2, 3, 4, ... Q.12. In Balmer series of hydrogen atom, as the wavelength of spectral lines decreases, they appear 1 (a) equally spaced and equally intense. (b) further apart and stronger in intensity. (c) closer together and stronger in intensity. (d) closer together and weaker in intensity. Note: For questions number 13 to 16, two statements are given—one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A). (b) Both Assertion (A) and Reason (R) are true and Reason (R) is not the correct explanation of Assertion (A). (c) Assertion (A) is true and Reason (R) is false. (d) Iboth Assertion (A) and Reason (R) are false. Q.13. Assertion (A): Electrons are ejected from the surface of zinc when it is irradiated by yellow light. 1 Reason (R): Energy associated with a photon of yellow light is more than the work function of zinc. Q.14. Assertion (A): The temperature coefficient of resistance is positive for metals and negative for p–type semiconductors. 1 Reason (R): The charge carriers in metals are negatively charged, whereas the majority charge carriers in p–type semiconductors are positively charged. Q.15. Assertion (A): When electrons drift in a conductor, it does not mean that all free electrons in the conductor are moving in the same direction. 1 Reason (R): The drift velocity is superposed over large random velocities of electrons. Q.16. Assertion (A): In interference and diffraction of light, light energy reduces in one region producing a dark fringe. It increases in another region and produces a bright fringe. 1 Reason (R): This happens because energy is not conserved in the phenomena of interference and diffraction.
Shiv Das 296  Shivdas SENIOR SECONDARY SERIES (XII) Section-B 5×2=10 Q.17. Draw the circuit diagram of a p–n junction diode in (i) forward biasing and (ii) reverse biasing. Also draw its I–V characteristics in the two cases. 2 Q.18. A proton and α–particle are accelerated through different potentials V1 and V2 respectively so that they have the same de Broglie wavelengths. Find V V 1 2 . 2 Q.19. A ray of light is incident normally on one face of an equilateral glass prism of refractive index μ. When the prism is completely immersed in a transparent medium, it is observed that the emergent ray just grazes the adjacent face. Find the refractive index of the medium. 2 Q.20. Two electric heaters have power ratings P1 and P2 at voltage V. They are connected in series to a dc source of voltage V. Find the power consumed by the combination. Will they consume the same power if connected in parallel across the same source? 2 Q.21. (a) An air bubble is trapped at point B (CB = 20 cm) in a glass sphere of radius 40 cm and refractive index 1.5 as shown in figure. Find the nature and position of the image of the bubble as seen by an observer at point P. 2 Or (b) In normal adjustment, for a refracting telescope, the distance between objective and eye piece lens is 1.00 m. If the magnifying power of the telescope is 19, find the focal length of the objective and the eyepiece lens. 2 Section-C 7×3=21 Q.22. (a) Differentiate between nuclear fission and fusion. (b) The fission properties of 94Pu239 are very similar to those of 92U235 . How much energy (in MeV), is released if all the atoms in 1 g of pure 94Pu239 undergo fission? The average energy released per fission is 180 MeV. 3 Q.23. The electric field in a region is given by E → = (10x + 4) i where x is in m and E is in N/C. Calculate the amount of work done in taking a unit charge from 3 (i) (5 m, 0) to (10 m, 0) (ii) (5 m, 0) to (5 m, 10 m) Q.24. Draw the graph showing variation of scattered particles detected (N) with the scattering angle (θ) in Geiger–Marsden experiment. Write two conclusions that you can draw from this graph. Obtain the expression for the distance of closest approach in this experiment. 3 Q.25. Find the current in branch BM in the network shown: 3 N M H G R F A B C D R E 6 E 4 R 4 R 4 R 2 R 3 R 10 E 2 R B C = 1.5 P