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Question 31355
JEE Physics · Hard

Waves on String: Phase Velocity MCQ

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Phase VelocityHardQuestion 31355

Question

Dispersive waves on a deep water string: phase velocity v_p = √(g/k) and group velocity v_g = v_p/2. A wave packet (pulse) on deep water travels at:
  1. A
    v_p
  2. B
    2v_p
  3. C
    v_p/2
    Correct
  4. D
    Zero

Correct answer

v_p/2

Explanation

Energy and information travel at group velocity v_g = v_p/2 for deep water gravity waves. Individual wave crests move at v_p but the envelope (packet) moves at v_g.

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