Question

Which physical quantity among the following remains unchanged when sound wave is reflected from a plane surface ?
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Answer 1

Wavelength, frequency and speed of the sound waves remain the same. These quantities remain same because reflection is bouncing of a wave in to the same medium. As because the medium remains same velocity remains same.

Now velocity of a sound wave is related to its frequency and wavelength by the relation V = νλ.

Hope its help you!

Answer 2

Answer:

frequency.

Explanation:

frequency remains unchanged when sound wave is reflected from a plane surface.