In a photoelectric effect, electrons are emitted

Options

A. with a maximum velocity proportional to the frequency of the incident radiation
B. at a rate that is independent of the intensity of the incident radiation
C. only if the frequency of the incident radiation is above a certain threshold value
D. only if the temperature of the emitter is high

Answer

C

Explanation

`KE_(max)=hv-phi`
`implies(1)/(2)mv_(max)^(2)=hv-phi`
`impliesv_(max)=sqrt((2(hv-phi)/(m)))`
Hence, (a) is incorrect.
Since `n=((IA)/(hv))`, therefore rate of emission of electrons is proportional to the intensity (I).
`KE_(max)=hv-phi`
Hence,(c ) is true.