PHY113-2 (EM waves)

Two straight wires connected to the terminals of an AC generator can create an

• magnetic field generation
• static electricity
• electromagnetic wave

• direct current (DC) flow

The current used to generate the electric wave creates a magnetic field.

• True

• False

The speed of an electromagnetic wave in a vacuum is:

A radio wave can be detected with a receiving antenna wire that is parallel to the electric field.

• True

• False

Even without a receiving antenna in the form of a loop, the magnetic field of a radio wave can be detected.

• True

• False

Answer explanation

With a receiving antenna in the form of a loop, the magnetic field of a radio wave can be detected.

Like all waves, electromagnetic waves have a wavelength and frequency, related by:

The speed of light in a vacuum

Maxwell's prediction of the speed of light

Electromagnetic waves, like water waves, carry energy.

• True

• False

Electromagnetic waves also can exhibit a Dopper effect, but it differs for two reasons:

• Sound waves require a medium, whereas electromagnetic waves do not.

• For sound, it is the motion relative to the medium that is important. For electromagnetic waves, only the relative motion of the source and observer is important.

• Sound waves require a medium like electromagnetic waves.

• For sound, it is the motion relative to the medium that is important. For electromagnetic waves, only the relative motion of the source is important.