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JAMB Physics 1978 Question 47

Question 47

Waves

A string is sustaining a stationary wave when

  1. A.the frequency of the wave is not proportional to the wavelength of the wave
  2. B.the amplitude of vibration is always zero
  3. C.two equal waves are travelling in opposite directions
  4. D.the waves are longitudinal
  5. E.the frequency is directly proportional to the length of the string.
Show the answer and explanation

Answer: C (two equal waves are travelling in opposite directions)

Explanation

A stationary wave forms when two waves of the same frequency and amplitude travel in opposite directions and superpose, e.g. a wave and its reflection.