Show that the radiation pressure exerted by an EM wave of intensity I on a surface kept in vacuum is I/c.
Assume that the surface is exposed to electromagnetic radiations. So, all the radiations are allowed to fall normally on the given surface.
Let the intensity of the radiation is I and the area of the surface is A.
So, the energy received by the surface in each second is given by,
E = I. A
So, number of photons received by surface in each second is given by,
For the perfectly absorbing surface,
So, force is given by,
Pressure is given by,
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