Concept:The threshold frequency is the minimum frequency of incident radiation required to eject photoelectrons from a metal surface.
Explanation:For photoelectric emission, an electron is ejected only when the energy of the incident photon is at least equal to the work function of the metal.
The energy carried by each photon is given by
E=hf, where
h is Planck's constant and
f is the frequency of the radiation.
The threshold frequency, denoted as
f0, is the value of
f at which the photon energy exactly equals the work function.
At this frequency, photoelectrons are just emitted with zero kinetic energy.
If the frequency falls below
f0, no photoelectrons are emitted no matter how intense the radiation is, because each photon individually lacks the minimum energy needed.
Hence, the threshold frequency sets the lower limit of photon frequency necessary for electron emission.
Answer:B. minimum frequency of incident radiation required to eject electrons