A metal is illuminated with light of frequency less than its threshold frequency. Which outcome is correct?
APhotoelectrons are emitted with small kinetic energy
BPhotoelectrons are emitted only if intensity is very high
CNo photoelectric emission occurs
DEmission occurs, but stopping potential is negative
Answer & Solution
Correct answer: C. No photoelectric emission occurs
For photoelectric emission, the photon energy must be at least equal to the work function: $h\nu \ge \phi_0$, or equivalently $\nu \ge \nu_0$. If $\nu<\nu_0$, no electrons are emitted no matter how large the intensity is. This is a key result supporting the particle nature of light.
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