Magnetic effect of current Worksheet-2

Magnetic effect of current Worksheet-2

1. The magnetic field produced due to a circular wire at its centre is :

A. in the plane of the wire

B. perpendicular to the plane of the wire

C. at 45° to the plane of the wire

D. at 60° to the plane of the wire.

2. A magnetic field exerts no force on :

A. an electric charge moving perpendicular to its direction

B. an unmagnetised iron bar

C. a stationary electric charge

D. a magnet

3. At the centre of a magnet, the magnetism is :

A. maximum                                 B. minimum

C. zero                                             D. same as at the poles

4. Induced current flows through a coil:

A. only for the period

B. less than the period

C. more than the period during which flux changes through it

D. none of these

5. Which of the following instruments works by electromagnetic induction ?

A. telephone receiver

B. simple motor

C. dynamo

D. moving coil galvanometer.

6. A DC generator is based on the principle of:

A. energy dissipation

B. electromagnetic induction

C. magnetic effect of current

D. heating effect of current.

7. The use of fuses in electric power-lines is :

A. to keep main voltage constant

B. to open the line permanently when there is an overload

C. just to show an indication when there is an overload

D. as a switch to use in an emergency.

8. An induced emf is produced when a magnet is introduced into a coil. The magnitude of this induced emf does not depend on :

A. the speed with which the magnet is moved

B. the number of turns of the coil

C. the strength of the magnet

D. the resistivity of the wire.

9. Dynamos and motors are based on :

A. Faraday's law

B. Ampere's force law

C. Faraday's law and Ampere's force law respectively

D. Ampere force law and Faraday's law respectively.

10. When the main switch of the house circuit is put off, it disconnects the :

A. live wire                                     B. neutral wire

C. earth wire                                  D. live and neutral wires.

Answer Key:

1. B
2. C
3. C
4. A
5. C
6. B
7. B
8. D
9. C
10. D