The Magnetic Effect of a Current-carrying Conductor

Diagram shows a compass is placed horizontally on a piece of cardboard and it is initially points north.

When the current is switched on, the compass needle will ....

• move to the west

• move to the east

• remain to the north

• vibrate at the original positiion

Diagram shows two compasses M and N are placed surrounding a straight wire carrying a current.

What will happen to the compasses needle when switch S is turned on?

• Both compasses will deflect 90° in an opposite direction.

• Both compasses will deflect 90° in the same direction.

• Both compasses will deflect 180°

• Compass M will deflect 180° while compass N will remain at the same position.

Diagram shows a magnetic field pattern which is produced from an experiment. The magnetic field pattern is due to ...

• coil

• straight wire

• solenoid

• magnetic bar

Diagram shows a solenoid carrying current.

Which of the following shows the correct pattern and direction of the magnetic field produced.

• 
• 
• 
• 

The diagram shows an electromagnet PQR,

What is the magnetic polarity at P, Q and R?

• P - North, Q - South, R - South

• P - South, Q - North, R - North

• P - South, Q - North, R - South

• P - North, Q - South, R - North

Diagram shows a copper wire coiled round a U-shaped soft iron core. The copper wire is connected to a battery.

When the switch is turned on, the magnetic pole of X, Y and Z are ...

• X - North, Y - North, Z - South

• X - North, Y - South, Z - North

• X - South, Y - North, Z - North

• X - South, Y - North, Z - South

Diagram shows two iron core are coiled round with a wire.

What happen to A and B when current flows?

• A and B are stationary

• A and B are attract to each other

• A and B repel at each other

• A and B repel first, then attract

The diagram shows two iron nails are hung freely in a solenoid.

When the current flows through the solenoid, the nails will

• be at their original position

• attract to each other

• repel at each other

• oscillate with a constant velocity

Which of the following shows the correct polarity of the electromagnet?

• 
• 
• 
• 

Diagram shows the apparatus used to study the effect of an electromagnet.

Which change will increase the number of paper clips attracted to the iron rod?

• Use a thinner wire to form the coils

• Use a non-isulated wire to form the coils

• Reduce the number of coils

• Increase the magnitude of the current