Light of uniform intensity shines perpendicularly on a totally absorbing surface, fully illuminating the surface. If the area of the surface is decreased:
A) the radiation pressure increases and the radiation force increases
B) the radiation pressure increases and the radiation force decreases
C) the radiation pressure stays the same and the radiation force increases
D) the radiation pressure stays the same and the radiation force decreases
E) the radiation preassure decreases and the radiation force decreases

Question

Quizplus · Accepted Answer

The radiation pressure depends on the intensity of the light and the reflection and absorption properties of the surface, but not on the surface area. Therefore, the radiation pressure stays the same. However, since the force exerted by the radiation pressure is proportional to the area, decreasing the area will decrease the radiation force.

Light of Uniform Intensity Shines Perpendicularly on a Totally Absorbing