Photons with energy `5 eV` are incident on a cathode C, on a photoelectric cell. The maximum energy of the emitted photoelectrons is `2 eV`. When photon of energy `6 eV` are incident on C, no photoelectron will reach the anode A if the stoppin potential of A relative to C is

Options

A. `-1V`
B. `-3V`
C. `+3V`
D. `+4V`

Answer

B

Explanation

In first case,
`eV_s =1/2 mv_("max")^2 = hv-phi_0`
`2 = 5 - phi_0 implies phi_0 =3eV`
In second case,
`eV_s = 6 - 3 = 3 eV implies V_s = 3 V`
`:.V_(AC )= -3 V.`