What happens when compressions of one wave line up with rarefactions of an interfering wave?

• A. In phase
• B. Constructive interference
• C. Destructive interference
• D. Standing wave

Answer: (C)

When compressions of one wave align with rarefactions of an interfering wave, this results in destructive interference. In terms of wave behavior, compressions represent areas of high pressure, while rarefactions correspond to areas of low pressure. When these two elements interact, they effectively cancel each other out, leading to a reduction in amplitude for the resultant wave.

This effect can be illustrated through the concept of superposition, where the resultant displacement of overlapping waves at any point in time is the algebraic sum of their individual displacements. When a compression (positive displacement) overlaps with a rarefaction (negative displacement), their contributions offset each other, thereby leading to a net decrease in amplitude. This is the hallmark of destructive interference; hence the correct answer is associated with this phenomenon.

In this context, other choices like 'in phase' or 'constructive interference' do not apply since those terms refer to scenarios where waves reinforce one another or align in a way that amplifies the resultant amplitude. A standing wave, on the other hand, is formed through the interference of two waves traveling in opposite directions, which is not the specific situation described in the question.