# Magnetic Field Due to Electric Current MCQ [Free PDF] – Objective Question Answer for Magnetic Field Due to Electric Current Quiz

1. The force existing between two infinite parallel conductors is inversely proportional to ________

B. Current in one of the conductors
C. The product of the current in the two conductors
D. The distance between the two conductors

When current is flowing in two different conductors, the force between the two conductors is directly proportional to the product of the current in the two conductors and inversely proportional to the distance between the two conductors.

2. When the distance of operation between the two conductors increases, what happens to the force between the two conductors?

A. Increases
B. Decreases
C. Remains the same
D. Becomes zero

When the distance of separation increases, the force between the two conductors decreases because the force between two conductors is inversely proportional to the distance of separation between them.

3. Magnetic field at a point d distance away from long wire due to electric current I in it is ____________

A. µ0i/2r
B. µ0i/r
C. µ0i/2πr
D. µ0i/πr

The magnetic field at distance d from long wire with carrying current i is given by-

B = µ0i/2πr.

4. The force per unit length existing between two infinite parallel conductors is given by ___________

A. µ0i1i2/2πd
B. µ0i1i2/2d
C. µ0i1/2πdi2
D. µ0i1i2/d

Force of the infinite conductor is given by Bil if B, I, and l are mutually perpendicular

F/l = Bi = µ0i1i2/2πd

where d is the separation of two infinite parallel conductors.

5. If the radius of the current-carrying conductor increases, what is the effect on the force?

A. increases
B. decreases
C. remain same
D. become zero

Force of the infinite conductor is given by Bil if B, I, and l are mutually perpendicular

F/l = Bi = µ0i1i2/2πd

where

d is the separation of two infinite parallel conductors. It doesn’t depend on the radius of the conductor so the force remains the same.

6. If the current of the conductor increases, what is the effect on the force?

A. increases
B. decreases
C. remain same
D. become zero

The Force of the infinite conductor is given by Bil

where

B, I, and l are mutually perpendicular

F/l = Bi = µ0i1i2/2πd

where

d is the separation of two infinite parallel conductors. So, as current increases force increases.

7. If the length of the current-carrying conductor increases, what is the effect on the force?

A. increases
B. decreases
C. remain same
D. become zero

Force of the infinite conductor is given by Bil where

B, I, and l are mutually perpendicular

F/l = Bi = µ0i1i2/2πd

Where

d is a separation of two infinite parallel conductors. So, as the length of the conductor increases force increases.

8. The magnetic field strength of a solenoid can be increased by inserting which of the following materials as the core?

A. Copper
B. Silver
C. Iron
D. Aluminium

The Magnetic field of a solenoid increases when we insert an iron core because iron is a ferromagnetic material and ferromagnetic materials help in increasing the magnetic property.

9. If a coil is wound around a steel core and electric current is passed through the coil, the steel core acts as a?

A. Electromagnet
B. Permanent magnet
C. Neither electromagnet nor permanent magnet
D. Either electromagnet or permanent magnet

When a coil is wound around a steel core, the steel core behaves like a permanent magnet because it is a ferromagnetic material and once it becomes magnetic it does not lose its magnetic property.

10. What is the formula for the magnetic field due to a solenoid?

A. μnI
B. μn2
C. μNI
D. μN2I2