Question

Cancellation (destructive interference) occurs at superposition of a crest and a(n):

Answer 1

A noise-cancellation speaker emits a sound wave with the same amplitude but with inverted phase (also known as antiphase) to the original sound. The waves combine to form a new wave, in a process called interference, and effectively cancel each other out – an effect which is called destructive interference.
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Answer 2

Answer:

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Explanation:

When two waves of same frequency and different or same amplitude superimpose at a point then the resultant displacement of that point is superposition of the displacement due to each wave.

When two such waves are superimposed in opposite phase then the resultant displacement will be minimum and this is known as destructive interference.

While if two waves are superimposed in same phase then the resultant of two will be maximum and it is known as constructive interference

Now here for cancellation or destructive interference since opposite phase is required so the correct answer for opposite phase of crest is

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