Why is photoelectric emission not possible at all frequencies? What is the special name given to such a frequency?

Solution:

Photoelectric effect

1. In the photoelectric effect, when a beam of light of a particular frequency is incident on the surface of a metal, the electrons are emitted from the surface of the metal.
2. The threshold frequency is the minimum required frequency for photoelectric emission.
3. For values smaller than threshold frequency the effect is not possible regardless of the intensity of incident light.

The threshold frequency is the special name given to such a frequency.