Moving Charges and Magnetism MCQ Questions for Class 12 Physics Chapter 4 with Answers

# Moving Charges and Magnetism MCQ Questions for Class 12 Physics Chapter 4 with Answers

Find here the NCERT chapter-wise Multiple Choice Questions from Class 12 Physics book Chapter 4 Moving Charges and Magnetism with Answers Pdf free download. This may assist you to understand and check your knowledge about the chapters. Students also can take a free test of the Multiple Choice Questions of Moving Charges and Magnetism. Each question has four options followed by the right answer. These MCQ Questions are selected supported by the newest exam pattern as announced by CBSE.

## Q1. The nature of parallel and anti-parallel currents are

(i) parallel currents repel and antiparallel cur¬rents attract.
(ii) parallel currents attract and antiparallel cur-rents repel.
(iii) both currents attract. ’
(iv) both currents repel.

(ii) parallel currents attract and antiparallel cur-rents repel.

## Q2. Which of the following shows that the earth behaves as a magnet?

(i) Repulsion between like poles .
(ii) Attraction between unlike poles
(iii) Null points in the magnetic field of a bar magnet
(iv) No existence of isolated magnetic poles

(iii) Null points in the magnetic field of a bar magnet

## Q3. In a cyclotron, a charged particle

(i) undergoes acceleration all the time.
(ii) speeds up between the dees because of the magnetic field.
(iii) speeds up in a dee.
(iv) slows down within a dee and speeds up between dees.

(i) undergoes acceleration all the time.

## Q4. A charged particle will not move with a constant velocity in a region where in,

(i) E = 0, B ≠ 0
(ii) E ≠ 0, B ≠ 0
(iii) E ≠ 0, B = 0
(iv) E = 0, B = 0.

(iii) E ≠ 0, B = 0

## Q5. An electron is projected with uniform velocity along the axis of a current carrying long solenoid. Which of the following is true?

(i) The electron will be accelerated along the axis.
(ii) The electron path will be circular about the axis.
(iii) The electron will experience a force at 45° to the axis and hence execute a helical path.
(iv) The electron will continue to move with uniform velocity along the axis of the solenoid.

(iv) The electron will continue to move with uniform velocity along the axis of the solenoid.

## Q6. Which of the following is not correct about cyclotron?

(i) It is a machine to accelerate charged particles or ions to high energies.
(ii) Cyclotron uses both electric and magnetic fields in combination to increase the energy of charged particles.
(iii) The operation of the cyclotron is based on the fact that the time for one revolution of an ion is independent of its speed or radius of its orbit.
(iv) The charged particles and ions in cyclotron can move on any arbitrary path.

(iv) The charged particles and ions in cyclotron can move on any arbitrary path.

## Q7. The permeability of a paramagnetic substance is:

(i) very large
(ii) small but more than unity
(iii) less than unity
(iv) negative

(ii) small but more than unity

## Q8. An electron is projected with uniform velocity along the axis of a current carrying long solenoid. Which of the following is true?

(i) The electron will be accelerated along the axis.
(ii) The electron path will be circular about the axis.
(iii) The electron will experience a force at 45° to the axis and hence execute a helical path.
(iv) The electron will continue to move with uniform velocity along the axis of the solenoid.

(iv) The electron will continue to move with uniform velocity along the axis of the solenoid.

## Q9. Consider a wire carrying a steady current, l placed in a uniform magnetic field B perpendicular to its length. Consider the charges inside the wire. It is known that magnetic forces do no work. This implies that

(i) motion of charges inside the conductor is unaffected by B since they do not absorb energy.
(ii) some charges inside the wire move to the surface as a result of B.
(iii) if the wire moves under the influence of B, no work is done by the force.
(iv) if the wire moves under the influence of B, work is done by the magnetic force on the ions, assumed fixed within the wire.

(ii) some charges inside the wire move to the surface as a result of B.

## Q10. The conversion of a moving coil galvanometer into a voltmeter is done by

(i) introducing a resistance of large value in series.
(ii) introducing a resistance of small value in parallel.
(iii) introducing a resistance of large value in parallel.
(iv) introducing a resistance of small value in series.

(i) introducing a resistance of large value in series.

## Q11. A charged particle is moving in a cyclotron, what effect on the radius of path of this charged particle will occur when the frequency of the ratio frequency field is doubled?

(i) It will also be doubled.
(ii) It will be halved.
(iii) It will be increased by four times.
(iv) It will remain unchanged.

(iv) It will remain unchanged.

## Q12. The sensitivity of a tangent galvanometer can be increased by increasing:

(i) the radius of the coil
(ii) the external magnetic field
(iii) the number of turns of the coil
(iv) all the above

(ii) the external magnetic field

## Q13. Biot-Savart law indicates that the moving electrons (velocity v) produce a magnetic field B such that

(i) B ⊥ v.
(ii) B || v.
(iii) it obeys inverse cube law.
(iv) it is along the line joining the electron and point of observation.

(i) B ⊥ v.

## Q14. A wire of fixed length is turned to form a coil of one turn. It is again turned to form a coil of three turns. If in both cases same amount of current is passed, then the ratio of the intensities of magnetic field produced at the centre of a coil will be

(i) 9 times of first case
(ii) 1/9 times of first case
(iii) 3 times of first case 1
(iv) 1/3 times of first case

(i) 9 times of first case

## Q15. If a charged particle moves through a magnetic field perpendicular to it

(i) both momentum and energy of particle change.
(ii) momentum as well as energy are constant.
(iii) energy is constant but momentum changes.
(iv) momentum is constant but energy changes.

(iii) energy is constant but momentum changes.

## Q16. A moving coil galvanometer can be converted into an ammeter by

(i) introducing a shunt resistance of large value in series.
(ii) introducing a shunt resistance of small value in parallel.
(iii) introducing a resistance of small value in series.
(iv) introducing a resistance of large value in parallel.

(ii) introducing a shunt resistance of small value in parallel.

## Q17. What happens to the magnetic field at the centre of a circular current carrying coil if we double the radius of the coil keeping the current unchanged?

(i) halved
(ii) doubled
(iv) remains unchanged

(i) halved

## Q18. If a charged particle moves through a magnetic field perpendicular to it

(i) both momentum and energy of particle change.
(ii) momentum as well as energy are constant.
(iii) energy is constant but momentum changes.
(iv) momentum is constant but energy changes.

(iii) energy is constant but momentum changes.

(i) 1 : 2
(ii) 2 : 1
(iii) 1 : 4
(iv) 4 : 1

(i) 1 : 2

(i) MB
(ii) √3MB2
(iii) MB2
(iv) zero

(iv) zero

## Q21. A strong magnetic field is applied on a stationary electron. Then the electron

(i) moves in the direction of the field.
(ii) remained stationary.
(iii) moves perpendicular to the direction of the field.
(iv) moves opposite to the direction of the field.

(ii) remained stationary.

## Q22. A current carrying power line carries current from west to east. Then the direction of the magnetic field 2 m above it is :

(i) west to east
(ii) south to north
(iii) north to south
(iv) None of these

(iii) north to south

(i) 2010 Ω
(ii) 4050 Ω
(iii) 5040 Ω
(iv) 4960 Ω

(iv) 4960 Ω

## Q24. An electron and a proton enter a magnetic field perpendicularly. Both have same kinetic energy. Which of the following is true

(i) Trajectory of electron is less curved
(ii) Trajectory of proton is less curved
(iii) Both trajectories are equally curved
(iv) Both move on straight line path

(ii) Trajectory of proton is less curved

## Q25. A current loop placed in a non-uniform magnetic field experiences

(i) a force of repulsion.
(ii) a force of attraction.
(iii) a torque but not force.
(iv) a force and a torque.

(iv) a force and a torque.

## Q26. Which one of the following is correct statement about magnetic forces?

(i) Magnetic forces always obey Newton’s third law.
(ii) Magnetic forces do not obey Newton’s third law.
(iii) For very high current, magnetic forces obey Newton’s third law.
(iv) Inside low magnetic field, magnetic forces obey Newton’s third law.

(ii) Magnetic forces do not obey Newton’s third law.

## Q27. hich of the following is not a unit of magnetic induction?

(i) gauss
(ii) tesla
(iii) oersted
(iv) weber/metre²

(iii) oersted

## Q28. If the beams of electrons and protons move parallel to each other in the same direction, then they

(i) attract each other.
(ii) repel each other.
(iii) no relation.
(iv) neither attract nor repel.

(ii) repel each other.

## Q29. A positive charge enters in a magnetic field and travels parallel to but opposite the field. If experiences

(i) an upward force.
(ii) a downward force.
(iii) an accelerated force.
(iv) no force.

(iii) an accelerated force.

(i) 8 times
(ii) 4 times
(iii) 2 times
(iv) 16 times

(ii) 4 times

(i) 0°
(ii) 45°
(iii) 90°
(iv) 180°

(iii) 90°

## Q32. The gyro-magnetic ratio of an electron in an H-atom, according to Bohr model, is

(i) independent of which orbit it is in.
(ii) neutral
(iii) positive
(iv) increases with the quantum number n.

(i) independent of which orbit it is in.

(i) r²
(ii) r
(iii) 1r
(iv) 1r²

(iii) 1r

## Q34. Two a-particles have the ratio of their velocities as 3 : 2 on entering the field. If they move in different circular paths, then the ratio of the radii of their paths is

(i) 2 : 3
(ii) 3 : 2
(iii) 9 : 4
(iv) 4 : 9

(ii) 3 : 2

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