The CBSE Class 12 Physics Answer Keys will help students calculate their grades for the CBSE Term 1 exam. Students can check CBSE 12th Physics Question Paper 2021 with Answers from the section below.
Q1. An electric dipole placed in a non-uniform electric field will experience:
Ans. both force and torque
Q2. Let N1 be the number of electric field lines going out of an imaginary cube of side a that encloses an isolated point charge 2q and N2 be the corresponding number for an imaginary sphere of radius a that encloses an isolated point charge 3q. Then (N1/N2) is:
Ans. 2/3
Q3. In a circuit given below P ≠ R and the reading of the galvanometer is same with switch S open or closed. Then:
Ans. IR = IG
Q4. Two wires A and B, of the same material having length in the ratio 1:2 and diameter in the ratio 2:3 are connected in series with a battery. The ratio of the potential differences across the two wires respectively is:
Ans. 9/8
Q5. Two moving coil galvanometers G1 and G2 have the following particulars respectively:
N1 = 30, A1 = 3.6 x 10-3m2,, B1 = 0.25T
N2 = 42, A2 = 1.8 x 10-3m2,, B2 = 0.50T
The spring constant is same for both the galvanometers. The ratio of current sensitivity of G1 and G2 is:
Ans. 5:7
Q6. A current 1 is flowing through the loop as shown in the figure (MA=R, MB=2R). The magnetic field at the center of the loop is μ0I/R times.
Ans. 7/16 out of the plane of the paper
Q7. A capacitor and an inductor are connected in two different ae circuits with a bulb glowing in each circuit. The bulb glows more brightly when:
Ans. the number of turns in the inductor is increased.
Q8. A pure inductor of 318 mH and a pure resistor of 75 are connected in series to an ac source of 50 Hz. The voltage across 75 The resistor is found to be 150 V. The source voltage is:
Ans. 250 V
Q9. The electric potential at a point on the axis of a short electric dipole, at a distance x from the midpoint of dipole, is proportional to:
Ans. 1/(X)3
Q10. Let F1 the magnitude of the force between two small spares, charged to a constant potential in free space, and F2 be the magnitude of the force between them in a medium of dielectric constant K. Then (F1/F2) is:
Ans. K
Q11. Infinity resistance in a resistance box has:
Ans. A gap only.
Q12. A battery of 15 V and negligible internal resistance is connected across a 50 resistor. The amount of energy dissipated as heat in the resistor in one minute is:
Ans. 270 J
Q13. Lenz’s law in the consequence of the law of conservation of:
Ans. Energy
Q14. The vertical component of earth’s magnetic field at a place is (13) times the horizontal component. The angle of that place is:
Ans. 30 degrees
Q15. A long straight wire in the horizontal plane carries a current of 15 A in the north to south direction. The magnitude and the direction of magnetic field at a point 2-5 m east of the wire respectively are:β
Ans. 1-2T, vertically upward
Q16. The emf induced in a 10 H inductor in which current changes forms 11 A to 2 A in 9x(10)-1s is:
Ans. (10)2V
Q17. A charge q is placed at the center of the line joining two charges q and q. The system of the three charges will be in equilibrium id Q is:
Ans. – q4
Q18. Electric flux of an electric field E through an area dA is given by:
Ans. E.dA
Q19. In a potentiometer experiment, the balancing length with a cell is 120cm. When the cell is shunted with a 1 Ω resistance, the balancing length becomes 40 cm. The internal resistance of the cell is:
Ans. 2Ω
Q20. An electron is projected with velocity v along the x-axis of a current carrying long solenoid. Which of the following statements is true?
Ans. The path of electron will be helical
Q21. If the speed v of a charged particle moving in a magnetic field B (v is perpendicular to B) is halved, then the radius of its path will:
Ans. become half
Q22. A metal plate is getting heated. Which one of the following statements is incorrect?
Ans. It is placed in a space varying magnetic field that does not vary with time.
Q23. In an ac circuit the applied voltage and resultant current are E = E0 sin ωt and I = I0 sin (ωt + ⊼/2) respectively. The average power consumed in the circuit is:
Ans. Zero
Q24. The speed acquired by a free electron when accelerated from rest through a potential difference of 100V is:
Ans. 6×106 ms-1
Q25. Which of the following is not affected by the presence of a magnetic field?
Ans. A rectangular current loop with its plane parallel to the field
Q26. Two point charged +16q and -4q are located at x = 0, and x = L. The location of the point on the x-axis at which the resultant electric field due to these charges is zero, is:
Ans. 2L
Q27. An electric dipole of dipole moment 4 x 10-5 C-m, kept in a uniform electric field of 10-3 NC-1 experiences a torque of 2 x 10-8 Nm. The angle which dipole makes with the electric field is:
Ans. 30o
Q28. Three identical charges are placed at x-axis from left to right with adjacent charges separated by a distance d. The magnitude of the force on a charge from its nearest neighbour charge is F. Let i be the unit vector along +x axis, then the net force on each charge from left to right is:
Ans. (-5/4 Fi , 0 , +5/4Fi)
Q29. Two students A and B calculate the charge flowing through a circuit. A concludes that 300C of charge flows in 1 minute. B concludes that 3.125 x 1019 electron flows in 1 second. If the current is measured in the circuit is 5 A, then the current calculation is done by:
Ans. both A and B
Q30. The resistance of two wires having the same length and same area of the cross-section is 2 Ω and 8 Ω respectively. If the resistivity of 2 Ω wire is 2.65 x 10-8 Ω-m, then the resistivity of 8 Ω wire is:
Ans. 10.60 x 10-8 Ω-m
Q31. In a certain region electric field E and magnetic field B are perpendicular to each other. An electron enters the region perpendicular to the direction of both E and B moves undeflected. The speed of the equation is:
Ans. [E]/[B]
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FAQs
The CBSE Exam for Physics Class 12 was conducted on December 10, 2021.
The official answer keys will be released soon. You can find the unofficial answer keys on the websites of coaching centres and various institutes.
Class 12 Physics will be released by the CBSE board.
The official website of the CBSE Board is https://www.cbse.gov.in/
The answer keys of CBSE Class 12 might see slight variation but students can get a rough idea of their scores.