Physics Class XII Sample Question Paper 2024-25 PDF

SAMPLE QUESTION PAPER PHYSICS Subject Code – 042 CLASS – XII Academic Session 2024 – 25 Maximum Marks: 70...

SAMPLE QUESTION PAPER PHYSICS Subject Code – 042 CLASS – XII Academic Session 2024 – 25 Maximum Marks: 70 Time Allowed: 3 hours 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. mp = 1.7 x10-27 kg iv. e = 1.6 x 10-19 C v. µ0 = 4π x 10-7 T m 𝑨−𝟏 vi. h = 6.63 x10-34 J s vii. ε0 = 8.854 x10-12 𝑪𝟐 𝑵−𝟏 𝒎−𝟐 viii. Avogadro’s number = 6.023 X 𝟏𝟎𝟐𝟑 per gram mole  [SECTION – A] (16x1=16 marks) Q1. A uniform electric field pointing in positive X-direction exists in a region. Let A be the origin, B be the point on the X-axis at x = +1 cm and C be the point on the Y-axis at y = +1 cm. Then the potential at points A, B and C satisfy. (A) VA < VB (B) VA > VB. (C) VA < VC (D) VA > VC Q2. A conducting wire connects two charged conducting spheres of radii r1 and r2 such that they attain equilibrium with respect to each other. The distance of separation between the two spheres is very large as compared to either of their radii. The ratio of the magnitudes of the electric fields at the surfaces of the spheres of radii r1 and r2 is 𝑟 𝑟2 𝑟2 2 𝑟1 2 (A) 𝑟1 (B) (C) (D) 2 𝑟1 𝑟1 2 𝑟2 2 Q3. A long straight wire of circular cross section of radius ҅a᾿ carries a steady current I. The current is uniformly distributed across its cross section. The ratio of magnitudes of the magnetic field at a point a/2 above the surface of wire to that of a point a/2 below its surface is (A) 4:1 (B) 1:1 (C) 4: 3 (D) 3 :4 Q4. The diffraction effect can be observed in (A) sound waves only (B) light waves only (C) ultrasonic waves only (D) sound waves as well as light waves Q5. A capacitor consists of two parallel plates, with an area of cross-section of 0.001 m2, separated by a distance of 0.0001 m. If the voltage across the plates varies at the rate of 108 V/s, then the value of displacement current through the capacitor is (A) 8.85 × 10−3 𝐴 (B) 8.85 × 10−4 𝐴 (C) 7.85 × 10−3 𝐴 (D) 9.85 × 10−3 𝐴 Q6. In a series LCR circuit, the voltage across the resistance, capacitance and inductance is 10 V each. If the capacitance is short circuited the voltage across the inductance will be (A) 10 V (B) 10√2 V (C) 10/√2 V (D) 20 V Q7. Correct match of column I with column II is C-l (waves) C-ll (Production) (1) Infra-red P. Rapid vibration of electrons in aerials (2) Radio Q. Electrons in atoms emit light when they move from higher to lower energy level. (3) Light R. Klystron valve (4) Microwave S. Vibration of atoms and molecules (A) 1-P, 2-R, 3-S, 4-Q (B) 1-S, 2-P, 3-O, 4-R (C) 1-Q, 2-P, 3-S, 4-R (D) 1-S. 2-R, 3-P, 4-Q Q8. The distance of closest approach of an alpha particle is d when it moves with a speed V towards a nucleus. Another alpha particle is projected with higher energy such that the new distance of the closest approach is d/2. What is the speed of projection of the alpha particle in this case? (A) V /2 (B) √2 V (C) 2 V (D) 4 V Q9. A point object is placed at the centre of a glass sphere of radius 6 cm and refractive index 1.5. The distance of virtual image from the surface of the sphere is (A) 2 cm (B) 4 cm (C) 6 cm (D) 12 cm Q10. Colours observed on a CD (Compact Disk) is due to (A) Reflection (B) Diffraction (C) Dispersion (D) Absorption Q11. The number of electrons made available for conduction by dopant atoms depends strongly upon (A) doping level (B) increase in ambient temperature (C) energy gap (D) options (A) and (B) both Q12. If copper wire is stretched to make its radius decrease by 0.1%, then the percentage change in its resistance is approximately  (A) –0.4% (B) +0.8% (C) +0.4% (D) +0.2% 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 the 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. Q13. Assertion (A): On increasing the current sensitivity of a galvanometer by increasing the number of turns may not necessarily increase its voltage sensitivity. Reason(R) : The resistance of the coil of the galvanometer increases on increasing the number of turns. Q14. Assertion (A): In a hydrogen atom there is only one electron but its emission spectrum shows many lines. Reason (R): In a given sample of hydrogen there are many atoms each containing one electron; hence many electrons in different atoms may be in different orbits so many transitions from higher to lower orbits are possible. Q15. Assertion (A): Nuclei having mass number about 60 are least stable.. Reason (R): When two or more light nuclei are combined into a heavier nucleus then the binding energy per nucleon will decrease. Q16. Assertion (A): de Broglie's wavelength of a freely falling body keeps decreasing with time. Reason (R): The momentum of the freely falling body increases with time. [SECTION – B] (05x2=10 marks) Q17. A platinum surface having work function 5.63 eV is illuminated by a monochromatic source of 1.6 x 10 15 Hz. What will be the minimum wavelength associated with the ejected electron.  Q18. (I) A beam of light consisting of two wavelengths, 4000 Å and 6000 Å, is used to obtain interference fringes in a Young’s double-slit experiment. What is the least distance from the central maximum where the dark fringe is obtained? OR (II) In Young’s double-slit experiment using monochromatic light of wavelength λ, the intensities of two sources are I. What is the intensity of light at a point where path difference between wavefronts is λ/4? Q19. P and Q are two identical charged particles each of mass 4 × 10–26 kg and charge 4.8 × 10–19 C, each moving with the same speed of 2.4 × 105 m/s as shown in the figure. The two particles are equidistant (0.5 m) from the vertical Y -axis. At some instant, a magnetic field B is switched on so that the two particles undergo head-on collision. Find – (I) the direction of the magnetic field and (II) the magnitude of the magnetic field applied in the region. (for VI candidates) A proton is moving with speed of 2 x 105 m s–1 enters a uniform magnetic field B = 1.5 T. At the entry velocity vector makes an angle of 30° to the direction of the magnetic field. Calculate (a) the pitch of helical path described by the charge (b) Kinetic energy after completing half of the circle. Q.20. Binding energy per nucleon vs mass number curve for nuclei is shown in the figure. W, X, Y and Z are four nuclei indicated on the curve. Identify which of the following nuclei is most likely to undergo (i) Nuclear Fission  (ii) Nuclear Fusion. Justify your answer. (for V.I. Candidates) Binding energy per nucleon and mass number of the following nuclei are given in the below table Nuclei Binding energy per nucleon (MeV) Mass number W 7.5 190 X 8.0 90 Y 8.5 60 Z 5.0 30 Identify which of the following nuclei is most likely to undergo (i) Nuclear Fission (ii) Nuclear Fusion. Justify your answer. Q21. A cylindrical conductor of length l and cross-section area A is connected to a DC source. Under the influence of electric field set up due to source, the free electrons begin to drift in the opposite direction of the electric field. (I) Draw the curve showing the dependency of drift velocity on relaxation time.  (II) If the DC source is replaced by a source whose current changes its magnitude with time such that I = Io sin 2πνt , where ν is the frequency of variation of current, then determine the average drift velocity of the free electrons over one complete cycle. [SECTION – C ] (07x3=21 marks) Q22. (I) Identify the circuit elements X and Y as shown in the given block diagram and draw the output waveforms of X and Y. (II) If the centre tapping is shifted towards Diode D1 as shown in the diagram, draw the output waveform of the given circuit. (for V.I. candidates) Which device is used to convert AC into DC. State it’s underlying principle and explain its working. If the frequency of input AC to this device is 60 Hz, then what will be frequency of the output of this device. Q23. Find the expression for the capacitance of a parallel plate capacitor of plate area A and plate separation d when (I) a dielectric slab of thickness t and (II) a metallic slab of thickness t, where (t < d) are introduced one by one between the plates of the capacitor. In which case would the capacitance be more and why? Q24. (I) Draw a ray diagram for the formation of image by a Cassegrain telescope. (II)Why these types of telescopes are preferred over refracting type telescopes. (Write 2 points) (for V.I. Candidates) A Cassegrain telescope is built with an arrangement of two mirrors placing them 20 mm apart. If the radius of curvature of the large mirror is 200mm and the small mirror is 150mm, where will the final image of an object at infinity be? Q25. (I) Draw the energy band diagram for P-type semiconductor at (i) T=0K and (ii) room temperature. (II)In the given diagram considering an ideal diode, in which condition will the bulb glow (a) when the switch is open (b) when the switch is closed Justify your answer. (for V.I. Candidates) Explain briefly how (i) barrier potential is formed in p-n junction diode. (ii) Width of depletion region of the diode is affected when it is (a) forward biased, (b) reverse biased. Q26. A boy is holding a smooth, hollow and non-conducting pipe vertically with charged spherical ball of mass 10 g carrying a charge of +10 mC inside it which is free to move along the axis of the pipe. The boy is moving the pipe from East to West direction in the presence of magnetic field of 2T. With what minimum velocity, should the boy move the pipe such that the ball does not move along the axis. Also determine the direction of the magnetic field. Q27. A light ray entering a right-angled prism undergoes refraction at the face AC as shown in Fig. 1. (I) What is the refractive index of the material of the prism in Fig. 1?  2 (II) (a) If the side AC of the above prism is now surrounded by a liquid of refractive index , as 3 shown in Fig. 2, determine if the light ray continues to graze along the interface AC or undergoes total internal reflection or undergoes refraction into the liquid. (b) Draw the ray diagram to represent the path followed by the incident ray with the corresponding angle values. √2 (Given, 𝑠𝑖𝑛−1 ( ) = 54.6° ) √3 (for V.I. candidates) A ray of light is incident on an equilateral prism at an angle 3/4 th of the angle of the prism. If the ray passes symmetrically through the prism, find the (a) angle of minimum deviation, and (b) refractive index of the material of the prism. Q28. (I) State Gauss᾿s theorem in electrostatics. Using this theorem, derive an expression for the electric field due to an infinitely long straight wire of linear charge density . OR (II) (a) Define electric flux and write its SI unit. (b) Use Gauss᾿s law to obtain the expression for the electric field due to a uniformly charged infinite plane sheet of charge. [SECTION D] (02x4=08 marks) Q29. Case Study Based Question: Motion of Charge in Magnetic Field An electron with speed vo