Wave Interference

Interference

Happens when two waves meet. Two types:

Constructive Interference Destructive Interference

Constructive Interference

Crest meets crest and trough meets trough. Result is higher crests and lower troughs. Greater amplitude.

Constructive Interference

Constructive Interference

Destructive Interference

Crest meets trough. Reduced amplitude.

Destructive Interference

Destructive Interference

Interference

We’ve only dealt with interference between waves that have identical frequencies. Most interference occurs between waves

that have different frequencies and amplitudes.

The result is a combination of constructive and destructive interference.

Interference

Standing Waves

Created when two identical waves moving in opposite directions meet. Example: A wave meets its own

reflection. Wave appears to remain stationary. No net movement of energy.

Standing Waves

nodes

antinodes

Beats

Arise when waves with two slightly different frequencies interfere. Characterized by rhythmic increases and

decreases in amplitude. Frequency of beat depends on how close

the frequencies are. Very close frequencies = very slow beat Not as close frequencies = faster beat

Beats

Beats

PSP Illustration Tuning fork box demonstration