Chapter 4: Q12DQ (page 1072)
A light source radiates a sinusoidal electromagnetic wave uniformly in all directions. This wave exerts an average pressure p on a perfectly reflecting surface a distance R away from it. What average pressure (in terms of p) would this wave exert on a perfectly absorbing surface that was twice as far from the source?
Short Answer
The average pressure exerted on the surface twice as far from the source of light will be p/4.