## Radiation pressure (reflection)

Radiation pressure is the pressure exerted upon any surface exposed to electromagnetic radiation. The term can also refer to pressures generated by other forms of wave motion, e.g. acoustic radiation pressure. According to special relativity, the momentum of a photon is equal to its energy divided by the speed of light. thus, if absorbed, the pressure is the power flux density divided by the speed of light. If the radiation is totally reflected, the radiation pressure is doubled.

## $$2f\frac{a}{c}\mathrm{COS\Theta}$$

Here,c=speed of light,a=power density,f=force.

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