What is it called when a crest of one wave intersects or combines with the trough of a second wave?

What is it called when a crest of one wave intersects or combines with the trough of a second wave?

• A. Destructive interference
• B. Resonance
• C. Constructive interference
• D. A frequency of 1000 Hz

Answer: (A)

Destructive interference is the idea here. When two waves overlap and their displacements have opposite signs—one crest meeting a trough—their amplitudes subtract. If they’re equal in size, they can cancel each other out, leaving a much smaller or zero net wave. This happens because the positive displacement from the crest and the negative displacement from the trough oppose each other. This is different from constructive interference, where waves are in phase and their amplitudes add, making a larger wave. It’s also not about resonance, which is about a system responding strongly at a natural frequency, nor about a specific frequency value like 1000 Hz.

Destructive interference is the idea here. When two waves overlap and their displacements have opposite signs—one crest meeting a trough—their amplitudes subtract. If they’re equal in size, they can cancel each other out, leaving a much smaller or zero net wave. This happens because the positive displacement from the crest and the negative displacement from the trough oppose each other.

This is different from constructive interference, where waves are in phase and their amplitudes add, making a larger wave. It’s also not about resonance, which is about a system responding strongly at a natural frequency, nor about a specific frequency value like 1000 Hz.