R4RIN – MCQs, Mock Tests | CBES Board Class 12 CBES Board(Class 12-Physics)MCQ Questions with Answers(Chapter 4 Moving Charges and Magnetism)

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?

1. It will also be doubled.
2. It will be halved.
3. It will be increased by four times.
4. It will remain unchanged.

✅ Correct Answer: 4

Which of the following is not correct about cyclotron?

1. It is a machine to accelerate charged particles or ions to high energies.
2. Cyclotron uses both electric and magnetic fields in combination to increase the energy of charged particles.
3. 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.
4. The charged particles and ions in cyclotron can move on any arbitrary path.

✅ Correct Answer: 4

The nature of parallel and anti-parallel currents are

1. parallel currents repel and antiparallel cur¬rents attract.
2. parallel currents attract and antiparallel cur-rents repel.
3. both currents attract. ’
4. both currents repel.

✅ Correct Answer: 2

A current carrying loop is placed in a uniform magnetic field. The torqe acting on it does not depend upon

1. area of loop
2. value of current
3. magnetic field
4. None of these

✅ Correct Answer: 4

A moving coil galvanometer can be converted into an ammeter by

1. introducing a shunt resistance of large value in series.
2. introducing a shunt resistance of small value in parallel.
3. introducing a resistance of small value in series.
4. introducing a resistance of large value in parallel.

✅ Correct Answer: 2

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

1. introducing a resistance of large value in series.
2. introducing a resistance of small value in parallel.
3. introducing a resistance of large value in parallel.
4. introducing a resistance of small value in series.

✅ Correct Answer: 1

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

1. moves in the direction of the field.
2. remained stationary.
3. moves perpendicular to the direction of the field.
4. moves opposite to the direction of the field.

✅ Correct Answer: 2

In an inertial frame of reference, the magnetic force on a moving charged particle is F⃗ Its value in another inertial frame of reference will be

1. remained same
2. changed due to change in the amount of charge
3. changed due to change in velocity of charged particle
4. changed due to change in field direction

✅ Correct Answer: 3

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

1. Magnetic forces always obey Newton’s third law.
2. Magnetic forces do not obey Newton’s third law.
3. For very high current, magnetic forces obey Newton’s third law.
4. Inside low magnetic field, magnetic forces obey Newton’s third law.

✅ Correct Answer: 2

A charged particle is moving on circular path with velocity v in a uniform magnetic field B, if the velocity of the charged particle is doubled and strength of magnetic field is halved, then radius becomes

1. 8 times
2. 4 times
3. 2 times
4. 16 times

✅ Correct Answer: 2

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

1. 2:03
2. 3:2
3. 9:04
4. 4 : 9

✅ Correct Answer: 2