Magnetic Lorentz Force, Class 12 Physics NCERT Solutions

MCQ’s For All Chapters – Physics Class 12th

1. There will be total 10 MCQ in this test.
2. Please keep a pen and paper ready for rough work but keep your books away.
3. The test will consist of only objective type multiple choice questions requiring students to mouse-click their correct choice of the options against the related question number.
4. No negative marking for incorrect choice.
5. Please click on “Finish the Test” when you want to exit.
6. All the best – Happy Studying

1. An electron with a speed of 1.8 x 10⁶ m/s is moving in a circular orbit in a uniform magnetic field of 10^-4 Wb/m², the radius of the circular path of the electron is

10.63 m

1.063 m

106.3 m

0.1063 m

Your comments:

Question 1 of 10

2. A particle of charge 1.6 x 10^-19 C and mass 1.8 x 10^-27 kg is moving around the path of radius 2 x 10⁴ m with velocity 2.4 x 10⁶ m/s. The magnetic field necessary is (in Wb/m²)

13.5 x 10^-6

135 x 10^-6

0.135 x 10

1.35 x 10^-6

Your comments:

Question 2 of 10

3. The force acting on a charge q moving with velocity in a magnetic field  is given by

A

B

C

D

Your comments:

Question 3 of 10

4. A Charge is fired through a magnetic field. The magnetic force acting on it is maximum when the angle between the direction of motion and magnetic field is

π

zero

π/2

π/4

Your comments:

Question 4 of 10

5. The frequency () of charged particle, moving at right angles to the magnetic field is independent of

radius of circular trajectory (r)

magnetic induction (B)

speed of the particle (v)

both speed of the particle (v) and radius of trajectory (r).

Your comments:

Question 5 of 10

6. Two straight horizontal parallel wires are carrying the same current in same direction, d is the distnace between the wires. You are povided with a small freely suspended magnetic needle. At which of the following positions will the orientation of the needle be independent of the magnitude of current in the wires?

At a distance d/2 from any of the wires.

At a distance d/2 from any of the wires in the horizontal plane.

Anywhere on the circumference of a vertical circle of radius d ans centre half way between the wires.

At points half way between the wires in the horizontal plane.

Your comments:

Question 6 of 10

7. A proton enters a magnetic field with a velocity of m/s making an angle of 30° with the field. What is the force experienced by the proton if B = 3.0 T.

3.6x10^-14 N

1.2x^-14 N

4.8x^-14 N

2.4x^-14 N

Your comments:

Question 7 of 10

8. When a charged particle moves in a magnetic field, its kinetic energy always

remain constant

first increases then decreases.

decreases

increases

Your comments:

Question 8 of 10

9. A proton with 1MeV kinetic energy is moving in a circular path of radius R in a uniform magnetic field. What should be the energy of an α - particle to describe a circle of same radius in the same magnetic field?

2 MeV

0.5 MeV

1 MeV

4 MeV

Your comments:

Question 9 of 10

10. An electron is moving in a circular orbit in a magnetic field Wb/m², the time period of electron is

A

B

C

D

Your comments:

Question 10 of 10

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