Electromagnetism

1. A magnetic field is produced by the current in a long straight wire. The strength of the magnetic field increases if.

• The magnitude of the current increases

• The distance from the wire increases

• The length of the wire increases

1. Which of the following is true about the magnetic field

produced by a current in a circular coil?

• It is uniform inside the coil

• It is the weakest at the centre

• It is the strongest at the centre

• There is no magnetic field outside the coil

What is the effect of placing a piece of soft iron core inside a solenoid carrying current?

• The resistance of the solenoid decreases

• The current in the solenoid increases

• The magnetic field becomes stronger

An electromagnet is used in these apparatus except

• a telephone earpiece

• an a.c dynamo

• a compass

• a moving coil ammeter

Which electromagnet is the strongest?

• 
• 
• 
• 

The figure shows a rectangular coil of wire WXYZ connected with a dry cell and a switch S is placed on the surface a horizontal table. Two compasses P and Q are laid on the wire WX and XY respectively.

What will happen to the pointer of compass P and Q when the switch ,S is closed?

• P : North Q : North

• P : North Q : East

• P : South Q : East

• P : South Q : West

Diagram below shows a copper wire coiled round a

U-shaped iron. Which of the following describes the magnetic pole of X, Y and Z correctly?

• A

• B

• C

• D

Which of the following change will decrease the magnetic effect of the iron rod?

• Increase the current

• Use a thicker wire to form the coil

• Reduce the number of turns in the coil

• Use a coil with a bigger cross-sectional area

The motion of a conductor carrying current in an magnetic fields can be determine by

• Direction of current flow

• Right hand Grip Rule

• Fleming’s Right Hand Rule

• Fleming’s Left Hand Rule

A current carrying wire is in between the poles of a magnet. The direction of the force on the wire is:

• North

• East

• South

• West