Show that the radiation pressure exerted by an EM wave of intensity I on a surface kept in a vacuum is Ic.

Hint: The radiation pressure depends on the energy transferred to the surface.
Step 1: Find the momentum transferred.
Pressure=ForceArea=FA
Force is the rate of change of momentum.
i.e.,                        F=dpdt
Step 2: Find the radiant pressure.
Energy in time dt, U=pc or p=Uc
                      Pressure=1A.Uc.dt
                         Pressure=Ic            I=Intensity=UA.dt