Question

When light f=1.2x10^15 hz illuminates an aluminium surface , a stopping potential of 1.5V is needed to reduce photoelectric current to 0. Determine the minimum possible energy of light that can eject electrons from the metal?

Answer 1

Given information is insufficient to calculate the minimum possible energy of light that can eject electrons from the metal.

Explanation:

Recall the definition of Stopping potential the given quantity.

The negative potential applied on the collector of a photoelectric cell at which the photoelectric current becomes zero is called the stopping potential or cut off potential.

Expression

`q_eV_0 = K_max` ..........(1)

gives the relation between the electronic charge `q_e`, stopping potential `V_0` and `K_max` the maximum kinetic energy of the photoelectrons that are emitted. Goes without saying here that even when stopping potential has been applied, the electrons continue to be ejected at the same kinetic energy as predicted by

`K_max=h(nu-nu_0)`

where, `h` is Planck's Constant, `nu and nu_0` are the frequency of incident light and the threshold frequency for the metal respectively.

This equation (1) can not be used to calculate work function or the cutoff frequency `nu_0`.

A separate experiment needs to be carried out in which frequency of incident light needs to varied to ascertain threshold frequency and thus find out the minimum possible energy of light that can eject electrons from the metal.