Choose the correct alternative.

1. When does an electromagnet have a magnetic field?

always
newer
when the circuit is closed
when the circuit is closed

2. What does an electric lock not contain?

a clip
a clamp
an electromagnet

3. What is a coil?

a metal bolt
a permanent magnet
a conductor bundle
a conductor surface
a kind of battery

4. Which of the following things is moved by a speaker's electromagnet?

a permanent magnet
a conductor
electricity
the bottom of the speaker
the surface of the speaker

5. What makes an electric motor rotate?

magic
an electronic lock
an electromagnet
a battery
gravity

6. How can a coil be made into an even more powerful electromagnet?

by cooling it down
by insulating it
by opening the circuit
by placing a metal bolt inside it
by painting it white