MCQ Magnetic Effect of Electric Current Class 12 Physics Chapter 4

MCQ Magnetic Effect of Electric Current Class 12 Physics Chapter 4


1. Which of the following statements is correct?

a) A charged particle can be accelerated by a magnetic field.

b) A charged particle cannot be accelerated by a magnetic field.

c) The speed of a charged particle can be increased by a uniform magnetic field.

d) The speed of a charged particle can be increased by a nonuniform magnetic field.


2. A proton moves horizontally towards a vertical conductor carrying a current upwards. It will be deflected

a) to the left

b) to the right

c) upwards



3. A proton and an Alpha-particle with the same kinetic energy are moving in circular trajectories in a constant magnetic field. If rp and ra denote respectively the radii of the trajectories of these particles,

a) rp > ra

b) rp = ra

c) rp < ra

d) rp = ra

4.A circular loop of area 1cm2, carrying a current of 10A is placed in a uniform magnetic field of 0.1T perpendicular to the plane of the loop. The force on the loop due to magnetic field is

a) Zero


c) 10-2N

d) 1 N


5. Two long conductors separated by a distance d carry currents I1 and I2 in the same direction. They exert a force F on each other. Now the current in one of them is increased to two times and its direction is reversed. The distance is also increased to 3d. The new value of the force between them is

a) -2F



d)- F/3

6. A circular coil of one turn with radius R carrying a current I has a dipole moment M. Now the coil is opened and rewound to have two turns without altering the current. The new dipole moment of the coil is

a) M/2

b) 2M

c) M

d) 4M


7. In order to float a wire carrying current I with linear mass situs slot gacor density μ in the air , the direction and magnitude of magnetic field to be is (Current is passing left to right)

a) μg/I into the plane

b) μg/I vertically upward

c) μg/IL into the plane

d) μg/I L vertically upward


8.A galvanometer coil has a resistance of 100Ω and the meter shows full scale deflection for a current of 1mA. The shunt resistance required to convert the galvanometer into an ammeter of range 0 to 5A is about

a) 0.01 Ω

b) 0.1Ω

c) 0.02 Ω

d) 0.2 Ω

9.An infinitely long wire carries a current I from left to right direction. A circular coil of radius R is in contact with the wire and carries the same current in clockwise direction. What is the magnitude and direction of net magnetic field intensity at the centre of the coil?

a) ( 1-) out of the plane of the page

b) ( 1-) in to the plane of the page

c) ( 1+) out of the plane of the page

d) ( 1+) out of the plane of the page


10. If we increase the number of turns of the coil of the moving coil galvanometer what happens
to the sensitivity?

a)Current sensitivity remains constant but voltage sensitivity changes

b)Current sensitivity increases but voltage sensitivity remains same

c)Both of them increase

d) No change in them

Answer: (A) : Both are correct and reason is correct explanation of assertion.
Answer: (B) : Both are correct but reason is not the correct explanation of assertion.
Answer: (C) : Reason is wrong.
Answer: (D) : Both are wrong.

11. Assertion: If a charged particle is moving in a perpendicular uniform magnetic field then its K E does not change

Reason: Velocity of the charged situs judi slot online terbaik dan terpercaya particle is not changing in the magnetic field

12. Assertion: A linear solenoid carrying a current is an equivalent bar magnet
Reason: The field lines of a solenoid resemble that of a bar magnet

13. Assertion: Magnetic field of an atom is due to both, the orbital motion and spin motion of electrons
Reason: A moving charged particle produces magnetic field

14. Assertion: Two electrons projected in to a uniform magnetic field at right angles with two different velocities complete their circular paths in the same time
Reason: Time period of revolution does not depend on velocity of the charged particle

15. Assertion: The magnetic field along the axis of a thick current carrying conductor is zero
Reason: Electric current flows only on the surface of a conductor