CBSE / NCERT Class 12 Physics Practice Question Papers with Answers (2026-27)

Brain Grain · braingrain.in

Physics — Practice Paper · Set 1

Class: 12CBSE / NCERTMax Marks: 33

Name: ____________________Reg No: ____________

Part I — Multiple Choice Questions 5 × 1 = 5

Choose the correct answer. (Answer all questions.)

1.Which of the statements given in Exercise 14.1 is true for p-type semiconductos.a. Electrons are majority carriers and trivalent atoms are the dopants.b. Electrons are minority carriers and pentavalent atoms are the dopants.c. Holes are minority carriers and pentavalent atoms are the dopants.d. Holes are majority carriers and trivalent atoms are the dopants.[1]

2.In an n-type silicon, which of the following statement is true: (a) Electrons are majority carriers and trivalent atoms are the dopants. (b) Electrons are minority carriers and pentavalent atoms are the dopants. (c) Holes are minority carriers and pentavalent atoms are the dopants. (d) Holes are majority carriers and trivalent atoms are the dopants.a. Electrons are majority carriers and trivalent atoms are the dopants.b. Electrons are minority carriers and pentavalent atoms are the dopants.c. Holes are minority carriers and pentavalent atoms are the dopants.d. Holes are majority carriers and trivalent atoms are the dopants.[1]

3.In an unbiased p-n junction, holes diffuse from the p-region to n-region because (a) free electrons in the n-region attract them. (b) they move across the junction by the potential difference. (c) hole concentration in p-region is more as compared to n-region. (d) All the above.a. free electrons in the n-region attract them.b. they move across the junction by the potential difference.c. hole concentration in p-region is more as compared to n-region.d. All the above.[1]

4.When a forward bias is applied to a p-n junction, it (a) raises the potential barrier. (b) reduces the majority carrier current to zero. (c) lowers the potential barrier. (d) None of the above.a. raises the potential barrier.b. reduces the majority carrier current to zero.c. lowers the potential barrier.d. None of the above.[1]

5.Carbon, silicon and germanium have four valence electrons each. These are characterised by valence and conduction bands separated by energy band gap respectively equal to (Eg)C, (Eg) Si and (Eg )Ge. Which of the following statements is true? (a) (Eg) Si < (Eg )Ge < (Eg)C (b) (Eg)C < (Eg)Ge > (Eg) Si (c) (Eg)C > (Eg) Si > (Eg )Ge (d) (Eg)C = (Eg) Si = (Eg )Gea. (Eg)Si < (Eg)Ge < (Eg)Cb. (Eg)C < (Eg)Ge > (Eg)Sic. (Eg)C > (Eg)Si > (Eg)Ged. (Eg)C = (Eg)Si = (Eg)Ge[1]

Part II — Short Answer Questions 14 × 2 = 28

Answer briefly. (Answer all questions.)

6.A system has two charges qA = 2.5 × 10–7 C and qB = –2.5 × 10–7 C located at points A: (0, 0, –15 cm) and B: (0,0, +15 cm), respectively. What are the total charge and electric dipole moment of the system?[2]

7.How long can an electric lamp of 100W be kept glowing by fusion of 2.0 kg of deuterium? Take the fusion reaction as 2 2 3 1 1 2 H+ H He+n+3.27 MeV →[2]

8.Find the (a) maximum frequency, and (b) minimum wavelength of X-rays produced by 30 kV electrons.[2]

9.The radius of the innermost electron orbit of a hydrogen atom is 5.3×10–11 m. What are the radii of the n = 2 and n =3 orbits?[2]

10.Use the mirror equation to deduce that: (a) an object placed between f and 2f of a concave mirror produces a real image beyond 2f. (b) a convex mirror always produces a virtual image independent of the location of the object. (c) the virtual image produced by a convex mirror is always diminished in size and is located between the focus and the pole. (d) an object placed between the pole and focus of a concave mirror produces a virtual and enlarged image. [Note: This exercise helps you deduce algebraically properties of images that one obtains from explicit ray diagrams.][2]

11.A 4.5 cm needle is placed 12 cm away from a convex mirror of focal length 15 cm. Give the location of the image and the magnification. Describe what happens as the needle is moved farther from the mirror.[2]

12.A small pin fixed on a table top is viewed from above from a distance of 50cm. By what distance would the pin appear to be raised if it is viewed from the same point through a 15cm thick glass slab held parallel to the table? Refractive index of glass = 1.5. Does the answer depend on the location of the slab?[2]

13.Monochromatic light of wavelength 589 nm is incident from air on a water surface. What are the wavelength, frequency and speed of (a) reflected, and (b) refracted light? Refractive index of water is 1.33.[2]

14.A beam of light converges at a point P. Now a lens is placed in the path of the convergent beam 12cm from P. At what point does the beam converge if the lens is (a) a convex lens of focal length 20cm, and (b) a concave lens of focal length 16cm?[2]

15.Choose the correct alternative from the clues given at the end of the each statement: (a) The size of the atom in Thomson’s model is .......... the atomic size in Rutherford’s model. (much greater than/no different from/much less than.) (b) In the ground state of .......... electrons are in stable equilibrium, while in .......... electrons always experience a net force. (Thomson’s model/ Rutherford’s model.) (c) A classical atom based on .......... is doomed to collapse. (Thomson’s model/ Rutherford’s model.) (d) An atom has a nearly continuous mass distribution in a .......... but has a highly non-uniform mass distribution in .......... (Thomson’s model/ Rutherford’s model.) (e) The positively charged part of the atom possesses most of the mass in .......... (Rutherford’s model/both the models.)[2]

16.What is the focal length of a convex lens of focal length 30cm in contact with a concave lens of focal length 20cm? Is the system a converging or a diverging lens? Ignore thickness of the lenses.[2]

17.A heating element using nichrome connected to a 230 V supply draws an initial current of 3.2 A which settles after a few seconds to a steady value of 2.8 A. What is the steady temperature of the heating element if the room temperature is 27.0 °C? Temperature coefficient of resistance of nichrome averaged over the temperature range involved is 1.70 × 10–4 °C–1.[2]

18.A conducting sphere of radius 10 cm has an unknown charge. If the electric field 20 cm from the centre of the sphere is 1.5 × 103 N/C and points radially inward, what is the net charge on the sphere?[2]

19.The fission properties of 239 94 Pu are very similar to those of 23592 U . The average energy released per fission is 180 MeV. How much energy, in MeV, is released if all the atoms in 1 kg of pure 239 94 Pu undergo fission?[2]

🔑 Show Answer Key — Set 1

1. (d) Holes are majority carriers and trivalent atoms are the dopants.
2. (c) Holes are minority carriers and pentavalent atoms are the dopants.
3. (c) hole concentration in p-region is more as compared to n-region.
4. (c) lowers the potential barrier.
5. (c) $(E_g)_C>(E_g)_{Si}>(E_g)_{Ge}$ .
6. Total charge is zero; dipole moment is $-7.5\times10^{-8}\,\hat{k}\,\text{C m}$ .
7. About $1.6\times10^{12}\,\text{s}$ , or $5.0\times10^4$ years.
8. (a) $7.25\times10^{18}\,\text{Hz}$ . (b) $4.14\times10^{-11}\,\text{m}$ , or $0.0414\,\text{nm}$ .
9. $r_2=2.12\times10^{-10}\,\text{m}$ and $r_3=4.77\times10^{-10}\,\text{m}$ .
10. All four results follow directly from $1/v+1/u=1/f$ with the Cartesian sign convention.
11. The image is $6.7\,\text{cm}$ behind the mirror, with magnification $0.56$ . It is virtual, erect and diminished. As the needle is moved farther away, the image moves towards the focus and becomes smaller.
12. The pin appears raised by $5\,\text{cm}$ . The shift does not depend on the slab's location, as long as it is parallel to the table.
13. (a) Reflected light: wavelength $589\,\text{nm}$ , frequency $5.09\times10^{14}\,\text{Hz}$ , speed $3.0\times10^8\,\text{m s}^{-1}$ . (b) Refracted light: wavelength $443\,\text{nm}$ , frequency $5.09\times10^{14}\,\text{Hz}$ , speed $2.26\times10^8\,\text{m s}^{-1}$ .
14. (a) $7.5\,\text{cm}$ beyond the lens. (b) $48\,\text{cm}$ beyond the lens.
15. (a) no different from. (b) Thomson’s model; Rutherford’s model. (c) Rutherford’s model. (d) Thomson’s model; Rutherford’s model. (e) both the models.
16. $-60\,\text{cm}$ ; the system is diverging.
17. $8.7\times10^2\,^{\circ}\text{C}$ approximately.
18. $-6.7\times10^{-9}\,\text{C}$ .
19. $4.5\times10^{26}\,\text{MeV}$ .

Brain Grain · braingrain.in

Physics — Practice Paper · Set 2

Class: 12CBSE / NCERTMax Marks: 33

Name: ____________________Reg No: ____________

Part I — Multiple Choice Questions 5 × 1 = 5

Choose the correct answer. (Answer all questions.)

Part II — Short Answer Questions 14 × 2 = 28

Answer briefly. (Answer all questions.)

6.(a) For the telescope described in Exercise 9.27 (a), what is the separation between the objective lens and the eyepiece? (b) If this telescope is used to view a 100 m tall tower 3 km away, what is the height of the image of the tower formed by the objective lens? (c) What is the height of the final image of the tower if it is formed at 25cm?[2]

7.(a) Explain the meaning of the statement ‘electric charge of a body is quantised’. (b) Why can one ignore quantisation of electric charge when dealing with macroscopic i.e., large scale charges?[2]

8.A square coil of side 10 cm consists of 20 turns and carries a current of 12 A. The coil is suspended vertically and the normal to the plane of the coil makes an angle of 30º with the direction of a uniform horizontal magnetic field of magnitude 0.80 T. What is the magnitude of torque experienced by the coil?[2]

9.Three capacitors each of capacitance 9 pF are connected in series. (a) What is the total capacitance of the combination? (b) What is the potential difference across each capacitor if the combination is connected to a 120 V supply?[2]

10.Three capacitors of capacitances 2 pF, 3 pF and 4 pF are connected in parallel. (a) What is the total capacitance of the combination? (b) Determine the charge on each capacitor if the combination is connected to a 100 V supply.[2]

11.The amplitude of the magnetic field part of a harmonic electromagnetic wave in vacuum is B0 = 510 nT. What is the amplitude of the electric field part of the wave?[2]

12.(a) At what distance should the lens be held from the card sheet in Exercise 9.22 in order to view the squares distinctly with the maximum possible magnifying power? (b) What is the magnification in this case? (c) Is the magnification equal to the magnifying power in this case? Explain.[2]

13.From the relation R = R0A 1/3, where R0 is a constant and A is the mass number of a nucleus, show that the nuclear matter density is nearly constant (i.e. independent of A).[2]

14.What is the shape of the wavefront in each of the following cases: (a) Light diverging from a point source. (b) Light emerging out of a convex lens when a point source is placed at its focus. (c) The portion of the wavefront of light from a distant star intercepted by the Earth.[2]

15.An infinite line charge produces a field of 9 × 104 N/C at a distance of 2 cm. Calculate the linear charge density.[2]

16.(a) The peak voltage of an ac supply is 300 V. What is the rms voltage? (b) The rms value of current in an ac circuit is 10 A. What is the peak current?[2]

17.A 600pF capacitor is charged by a 200V supply. It is then disconnected from the supply and is connected to another uncharged 600 pF capacitor. How much electrostatic energy is lost in the process?[2]

18.Two charges 5 × 10–8 C and –3 × 10–8 C are located 16 cm apart. At what point(s) on the line joining the two charges is the electric potential zero? Take the potential at infinity to be zero.[2]

19.A parallel plate capacitor with air between the plates has a capacitance of 8 pF (1pF = 10–12 F). What will be the capacitance if the distance between the plates is reduced by half, and the space between them is filled with a substance of dielectric constant 6?[2]

🔑 Show Answer Key — Set 2

1. (d) Holes are majority carriers and trivalent atoms are the dopants.
2. (c) Holes are minority carriers and pentavalent atoms are the dopants.
3. (c) hole concentration in p-region is more as compared to n-region.
4. (c) lowers the potential barrier.
5. (c) $(E_g)_C>(E_g)_{Si}>(E_g)_{Ge}$ .
6. (a) $145\,\text{cm}$ . (b) $4.7\,\text{cm}$ . (c) About $28\,\text{cm}$ .
7. (a) A body's charge is an integral multiple of the elementary charge: $q=ne$ . (b) For macroscopic charges, $n$ is extremely large, so the charge appears continuous.
8. $0.96\,\text{N m}$ .
9. (a) $3\,\text{pF}$ ; (b) $40\,\text{V}$ across each capacitor.
10. (a) $9\,\text{pF}$ ; (b) charges are $200\,\text{pC}$ , $300\,\text{pC}$ and $400\,\text{pC}$ respectively.
11. $153\,\text{V m}^{-1}$ .
12. (a) $6.6\,\text{cm}$ . (b) $3.8$ . (c) With the eye close to the lens and final image at the near point, the linear magnification equals the angular magnifying power numerically.
13. Since nuclear mass is proportional to $A$ and nuclear volume is also proportional to $A$ , nuclear density is independent of $A$ .
14. (a) Spherical. (b) Plane. (c) Approximately plane.
15. $1.0\times10^{-7}\,\text{C m}^{-1}$ .
16. (a) $212\,\text{V}$ . (b) $14.1\,\text{A}$ .
17. $6.0\times10^{-6}\,\text{J}$ .
18. The potential is zero at a point between the charges, $10\,\text{cm}$ from the $+5\times10^{-8}\,\text{C}$ charge, and at a point outside on the side of the negative charge, $40\,\text{cm}$ from the positive charge.
19. $96\,\text{pF}$ .

Brain Grain · braingrain.in

Physics — Practice Paper · Set 3

Class: 12CBSE / NCERTMax Marks: 33

Name: ____________________Reg No: ____________

Part I — Multiple Choice Questions 5 × 1 = 5

Choose the correct answer. (Answer all questions.)

Part II — Short Answer Questions 14 × 2 = 28

Answer briefly. (Answer all questions.)

6.A long straight wire carries a current of 35 A. What is the magnitude of the field B at a point 20 cm from the wire?[2]

7.What is the magnitude of magnetic force per unit length on a wire carrying a current of 8 A and making an angle of 30º with the direction of a uniform magnetic field of 0.15 T?[2]

8.(a) A circular coil of 30 turns and radius 8.0 cm carrying a current of 6.0 A is suspended vertically in a uniform horizontal magnetic field of magnitude 1.0 T. The field lines make an angle of 60° with the normal of the coil. Calculate the magnitude of the counter torque that must be applied to prevent the coil from turning. (b) Would your answer change, if the circular coil in (a) were replaced by a planar coil of some irregular shape that encloses the same area? (All other particulars are also unaltered.)[2]

9.Consider a uniform electric field E = 3 × 103î N/C. (a) What is the flux of this field through a square of 10 cm on a side whose plane is parallel to the yz plane? (b) What is the flux through the same square if the normal to its plane makes a 60° angle with the x-axis?[2]

10.In a plane electromagnetic wave, the electric field oscillates sinusoidally at a frequency of 2.0 × 1010 Hz and amplitude 48 V m–1. (a) What is the wavelength of the wave? (b) What is the amplitude of the oscillating magnetic field? (c) Show that the average energy density of the E field equals the average energy density of the B field. [c = 3 × 108 m s–1.][2]

11.A long straight wire in the horizontal plane carries a current of 50 A in north to south direction. Give the magnitude and direction of B at a point 2.5 m east of the wire.[2]

12.A difference of 2.3 eV separates two energy levels in an atom. What is the frequency of radiation emitted when the atom make a transition from the upper level to the lower level?[2]

13.An angular magnification (magnifying power) of 30X is desired using an objective of focal length 1.25cm and an eyepiece of focal length 5cm. How will you set up the compound microscope?[2]

14.A pair of adjacent coils has a mutual inductance of 1.5 H. If the current in one coil changes from 0 to 20 A in 0.5 s, what is the change of flux linkage with the other coil?[2]

15.Obtain approximately the ratio of the nuclear radii of the gold isotope 197 79 Au and the silver isotope 10747 Ag .[2]

16.A battery of emf 10 V and internal resistance 3 Ω is connected to a resistor. If the current in the circuit is 0.5 A, what is the resistance of the resistor? What is the terminal voltage of the battery when the circuit is closed?[2]

17.A regular hexagon of side 10 cm has a charge 5 μC at each of its vertices. Calculate the potential at the centre of the hexagon.[2]

18.A horizontal overhead power line carries a current of 90 A in east to west direction. What is the magnitude and direction of the magnetic field due to the current 1.5 m below the line?[2]

19.Two charges 2 μC and –2 μC are placed at points A and B 6 cm apart. (a) Identify an equipotential surface of the system. (b) What is the direction of the electric field at every point on this surface?[2]

🔑 Show Answer Key — Set 3

1. (d) Holes are majority carriers and trivalent atoms are the dopants.
2. (c) Holes are minority carriers and pentavalent atoms are the dopants.
3. (c) hole concentration in p-region is more as compared to n-region.
4. (c) lowers the potential barrier.
5. (c) $(E_g)_C>(E_g)_{Si}>(E_g)_{Ge}$ .
6. $3.5\times10^{-5}\,\text{T}$ .
7. $0.60\,\text{N m}^{-1}$ .
8. (a) $3.1\,\text{N m}$ . (b) No, if the area and all other particulars remain the same.
9. (a) $30\,\text{N m}^2\text{C}^{-1}$ ; (b) $15\,\text{N m}^2\text{C}^{-1}$ .
10. (a) $1.5\times10^{-2}\,\text{m}$ . (b) $1.6\times10^{-7}\,\text{T}$ . (c) $\langle u_E\rangle=\langle u_B\rangle=\epsilon_0E_0^2/4$ .
11. $4.0\times10^{-6}\,\text{T}$ , vertically upward.
12. $5.6\times10^{14}\,\text{Hz}$ .
13. For final image at the near point, set the lens separation to about $12.5\,\text{cm}$ and place the object about $1.47\,\text{cm}$ in front of the objective.
14. $30\,\text{Wb-turn}$ .
15. $R_{\text{Au}}/R_{\text{Ag}}\approx1.23$ .
16. The external resistance is $17\,\Omega$ and the terminal voltage is $8.5\,\text{V}$ .
17. $2.7\times10^6\,\text{V}$ .
18. $1.2\times10^{-5}\,\text{T}$ , towards south.
19. (a) The plane perpendicular to AB through its midpoint is an equipotential surface of zero potential. (b) The electric field is perpendicular to this plane and directed from the positive charge towards the negative charge.

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