Light of frequency 1.5 times the threshold frequency is incident on a photodsensitive material . What will be the photoelectric current if frequency is halved and intensity is doubled

Options

A. Doubled
B. Four times
C. One-fourth
D. Zero

Answer

D

Explanation

`K_1 = 1.5 hv_0 - phi_0 = 0.5hv_0 implies phi_0 = hphi_0`
`K_2 = (1.5)/2 hv_0 - hv_0 = 0.25hv_0`
`:.` Kinetic energy can never be negative
So, no emission and i = 0
or
In second case the incident frequency is halved Incident frequency `= (1.5)/2 v_0 = 0.75 v_0`
Now, the incident frequency is less than threshold frequency so no emission of electrons takes place, Therefore no current (i = 0) .