A string is sustaining a stationary wave when

  • A the frequency of the wave is not proportional to the wavelength of the wave
  • B the amplitude of vibration is always zero
  • C two equal waves are travelling in opposite directions
  • D the waves are longitudinal
  • E the frequency is directly proportional to the length of the string
jamb 1978physics

The correct answer is C. two equal waves are travelling in opposite directions

-Standing waves are produced on a string when equal waves travel in opposite directions.

-A stretched string is fixed at both ends, when it is plucked at mid point, two reflected waves of same amplitude and frequency at the ends are travelling in opposite direction and overlap along the length. Then the resultant waves are known as the standing waves (or) stationary waves.

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