MCQs on Moving Charges and Magnetism – Ch-4 Class 12

Multiple Choice Questions with their answers on chpater -4 Moving Charges and Magnetism for class 12 NVERT.

All important questions are in one place to help the student revise the concepts.

A. What is the formula of Lorentz force

 q = charge

B = Magnetic Fields

E = Electric Fields

v = Velocity of charge

1. F = q (v + B + E)
2. F = q (v * B * E)
3. F = q (v * B + E)
4. F = q + (v + B + E)

Answer 3

B. A charged particle is moving in a circle, and the force acting on it is not zero. What would be gain in particle’s energy

1  Zero

2  Infinity since the particle is moving in a circle continuously 

3  Answer can not be obtained from the information provided

4  None of the above

Answer 1

C. According to Lorentz force concept if a charge is not moving then magnetic force on the charge is 

1. Four times as that of velocity
2. Zero
3. Same as that of electric force
4. None of the above

Answer 2 

D. For a point charge moving with a velocity v, the applied magnetic field is parallel to the velocity, what would be forced due to the magnetic field

1. Product of velocity and magnetic field
2. Infinity
3. Zero
4. One

Answer 3

E. Please pick the correct option 

1. The gravitational force depends on the intervening medium of two bodies while the electrostatic force does not depend upon the intervening medium between two charges
2. Both gravitational and electrostatic forces depend upon the interviewing medium of two bodies
3. Both gravitational and electrostatic forces do not depend upon the interviewing medium of two bodies
4. The gravitational force does not depend on the intervening medium of two bodies while the electrostatic force depends upon the intervening medium between two charges

Answer 4

F. A straight wire is held in the air and it is held there by the horizontal magnetic force. The mass of wire is 1 Kg and length is 10 m and it has a current of 10 A. What is the magnitude of the magnetic field

1. 9.8 T
2. 0.098 T
3. 0.98 T
4. 98 T

Answer 2

G. A particle has velocity v and traveling along the x-axis, the magnetic field B is along with y-axis. What would be the direction of magnetic force

1. x-axis
2. Y-axis
3. Z-axis
4. None of the above

Answer 3

H.  Please pick the correct statement

1. The frequency of revolution of a charged particle in a magnetic field is independent of energy
2. The frequency of revolution of a charged particle in a magnetic field is dependent  on energy
3. The frequency of revolution of a charged particle in a magnetic field is proportional to the energy
4. The frequency of revolution of a charged particle in a magnetic field is inversely proportional to the energy

Answer 1 

I. The cyclotron uses the following to increase the energy of charged particles

1. Electric field
2. Magnetic field
3. Sometimes electric and sometimes magnetic field
4. Electric and Magnetic fields

Answer 4

J. Please pick the correct statement

1. In a cyclotron, magnetic and electric fields are perpendicular to each other
2. In a cyclotron, magnetic and electric fields are parallel to each other
3. In a cyclotron, magnetic and electric fields are at 45 degrees to each other
4. In a cyclotron, only magnetic field exits

Answer 1

K.  Please pick the correct statement

1. In a cyclotron, the magnetic field makes the particle go round in a circular path
2. In a cyclotron, the electric field makes the particle go round in a circular path
3. In a cyclotron, the electric and magnetic field makes the particle go round in a circular path
4. In a cyclotron, the electric or magnetic field makes the particle go round in a circular path

Answer 1

L. In cyclotron, what causes the acceleration of charged particles

1. Magnetic field
2. Electric Field
3. Magnetic and Electric Field
4. Sometimes Magnetic sometimes Electric Field

Answer 2

M. What is resonance condition in cyclotron

1. The frequency of dees polarity adjustment is equal to the frequency of ions to complete one full  revolution
2. The frequency of dees polarity adjustment is equal to the frequency of ions to complete a parallel revolution
3. The frequency of dees polarity adjustment is equal to the frequency of ions to complete one half of the revolution
4. The frequency of dees polarity adjustment is equal to the frequency of ions to complete a prependicular revolution

Answer 3

N In cyclotron, time of revolution of an ion is not dependent on _________ of its orbit

1. Speed
2. Radius
3. Speed or Radius
4. None of the above

Answer 3

O The principle of superposition applies to: 

1. Biot-Sarvart Law of the magnetic field
2. Coulomb Law of an electrostatic field
3. Both 1 and 2
4. None of the above

Answer 3

P.________ source creates electrostatic field while _______ source creates magnetic field 

1. Scaler, Vector
2. Vector, Scaler
3. Scaler, Scaler
4. Vector, Vector

Answer 1

Q What is the magnetic field at the center due to the 10 A current flowing in a coil of 1 m

1. 62.83 * 10 – 1
2. 62.83 * 10 – 5
3. 62.83 * 10 – 3
4. 62.83 * 10 – 7

Answer 4

R. Using Ampere’s law find out the magnetic field of 5 amp current flowing in a circular loop with a radius 0.5 m

Magnetic field constant = 4*3.14 * 10  – 7

1. 1 * 10-6
2. 3 * 10-6
3. 4 * 10-6
4. 2 * 10-6

Answer 4