Interference pattern can be observed due to superposition of the following waves: (I) y = a sin ωt; (II) y = a sin 2ωt; (III) y = a sin(ωt - φ); (IV) y = a sin 3ωt. Choose the correct answer.
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Question

Interference pattern can be observed due to superposition of the following waves: (I) y = a sin ωt; (II) y = a sin 2ωt; (III) y = a sin(ωt − φ); (IV) y = a sin 3ωt. Choose the correct answer.

G1 Physics · Accepted Answer

Step 1: A sustained interference pattern needs two coherent waves with the same frequency and stable phase difference. Step 2: Wave (I) has angular frequency ω. Wave (III) also has frequency ω, phase shifted by fixed φ. Step 3: Waves (II) and (IV) have 2ω and 3ω and are not coherent with (I). Final answer: (C) (I) and (III).