Q138 / 180 · COMEDK 2015 · Physics

If the surface is a perfect reflector, then the change in momentum of the wave after falling on the surface is

  • A
    $p$
  • B
    $2 p$
  • C
    $\frac{p}{2}$
  • Correct answer
    D
    $-2 p$

Solution

$p$ is the momentum of incident wave. $\therefore$ Momentum of reflected wave after reflecting from perfect reflector $=-p$ $\therefore$ Change in momentum $=$ Final momentum - Initial momentum $$ =-p-p=-2 p $$

Hence, the correct answer is option: 'D'.

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