Magnetism 0221

In which pair are both materials magnetic?

• aluminium and copper

• copper and iron

• iron and steel

• steel and aluminium

Which diagram shows the poles of the magnets?

• A

• B

• C

• D

Which metal could be used for a permanent magnet and which metal could be used for the core of an electromagnet?

• A

• B

• C

• D

A wire perpendicular to the page carries an electric current in a direction out of the page. There are four compasses near the wire. Which compass shows the direction of the magnetic field caused by the current?

• A

• B

• C

• D

A coil carries a current in a magnetic field. The coil experiences a turning effect. Which device uses this effect?

• d.c. motor

• electromagnet

• relay

• transformer

The diagram shows a flat, rectangular coil placed between the poles of a magnet. THere is a current in the coil that makes it turn in the direction shown in the diagram. Which change would make the coil turn in the opposite direction?

• decreasing the current in the coil

• increasing the number of turns of the coil

• reversing both the direction of the current in the coil and the poles of the magnet

• reversing only the direction of the current in the coil

A current carrying coil in a magnetic field experiences a turning effect. How can the turning effect be increased?

• increase the number of turns on the coil

• reduces the size of the current

• reverse the direction of the magnetic field

• use thinner wire for the coil

The diagram shows a coil of wire connected to a voltmeter. A student has a magnet and an unmagnetised iron rod. How can an e.m.f. be induced across the coil?

• holding the magnet inside the coil

• holding the iron rod inside the coil

• pushing the magnet into the coil

• pushing the iron rod into the coil

Which device uses a moving wire to induce an e.m.f.?

• cathode ray tube

• generator

• transformer

• electromagnet

X and Y are joined, by four wires, each made of a different material. Each wire is then moved quickly downward between the magnets. Which materials will not give rise to an induced current in the wire?

• aluminium

• copper

• iron

• nylon