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QLDPhysicsQuick questions
Unit 2: Linear motion and waves
Quick questions on Superposition and interference of waves (QCE Physics Unit 2)
4short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What is treating interference as energy disappearing?Show answer
Energy is conserved. Nodes (zero amplitude) exist alongside antinodes (large amplitude). Average over a full interference pattern recovers the input energy.
What is confusing in-phase with same-amplitude?Show answer
Constructive interference requires the waves to be in phase. Same-amplitude does not by itself guarantee constructive.
What is forgetting that the rule flips for out-of-phase sources?Show answer
If the sources oscillate $180°$ out of phase (one peak corresponds to the other's trough), integer path differences give minima.
What is treating a small-amplitude resultant as no wave?Show answer
Two waves of slightly different frequencies superpose to give beats (a slowly modulating amplitude). The destructive moments are real instants of zero displacement, not silence.
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