Question

Electromagnetic radiation with a frequency of 8.6 x 1014 hz incident on an unknown metal surface causes ejection of photoelectrons with kinetic energies of 1.3 x 10–19 j. what is the unknown metal?

Answer 1

List of metals along with their work function will be provided to you in exams. Here, possible metal is silver(Ag).

Answer 2

Answer;

Silver metal

Explanation;

From the equation of photoelectric effect ;

hf = Wo + K.E

Where; hf is the energy of a photon of light, Wo is the work function, that is the minimum energy required to remove an electron from the surface of the material, and K.E is kinetic energy.

Work function= hf - kinetic energy ; h the Plank constant 6.63 x 10-34 J s

= (6.63 x 10-34 J s)×(8.6 x 10^14 hz) - ( 1.3 x 10–19 j)

= 4.4 × 10^-19

Thus; the work function of the metal is 4.4 × 10^-19

The possible metal is therefore; silver metal.