Two light beams of different frequency but the same intensity fall on a black (totally absorbing) surface, striking perpendicular to the surface. Which of the following statements are true? (There
Could be more than one correct choice.)
A) Painting the surface white would not affect the pressure on it due to these beams.
B) The high-frequency beam exerts more pressure on the surface.
C) Both beams exert the same pressure on the surface.
D) The light beams exert no pressure on the surface because light is just energy.
E) If the surface were painted white (totally reflecting), the pressure on it would be less than when it was black.

Question

Quizplus · Accepted Answer

The pressure exerted by light on a surface is determined by the intensity and the nature of the surface (absorbing or reflecting), not the frequency. Since both beams have the same intensity and the surface is totally absorbing, they exert the same pressure.

Two Light Beams of Different Frequency but the Same Intensity