Which metal is generally used for making electromagnets?

(A) Copper

(B) Cobalt

(C) Iron

(D) None of these

What are electromagnets used for?

Which statement is true of magnets?

a) Earth is an electromagnet

b) Electromagnets are weaker than permanant magnets

c) A magnet always has a north pole, and may or may not also has a south pole

d) A permanent magnet can be turned off.

• Select the best definition for wavelength.

1. The height of an oscillating electromagnetic wave.
2. The rate at which electromagnetic waves oscillate.
3. The distance between two crests of an electromagnetic wave.
4. The oscillations of electric and magnetic fields.

• Select the best definition for frequency.

1. The oscillations of electric and magnetic fields.
2. the height of an oscillating electromagnetic wave.
3. the distance between two crests of an electromagnetic wave.
4. The rate at which electromagnetic waves oscillate.