In the photoelectric effect, the following observations may be made.

I.     The kinetic energy of the emitted electrons increases with increasing light frequency.

II.     The electrons are emitted without time delay.

Which of these observations, if any, can be explained in terms of the wave theory of light?

A.     Neither I nor II

B.     I and II

C.     I only

D.     II only

A

The immediate nature of photoelectricity is often overlooked in textbooks. It is, however, part of the evidence for the photonic nature of light.