# Momentum in a Box of Light

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1. Jun 2, 2016

### DrPapper

1. The problem statement, all variables and given/known data

2. Relevant equations
<S>=c$\epsilon$E2/2

$\Delta P = A \Delta t <S>/c$

3. The attempt at a solution
My question is if we need the "box height"? This is my work which I'm assuming is wrong. :C

If there's another problem like this on here please put a link. I didn't see any, but my search terms may not have been ideal "Pressure of light in a box".

2. Jun 2, 2016

### Staff: Mentor

What is the momentum of the light? Why did 1400 W m-2 become 1000 W m-2? You didn't say why reflection doesn't change the answer.