Electrons and photons example | Learn Physics

Example of electrons and photons

Electrons and photons example:  To remove one of the least tightly bound electrons from a metal surface, 4.2 eV energy is to be spent. When ultraviolet photons of a single frequency strike a metal, electrons with kinetic energies from zero to 2.6 eV are ejected? What is the energy of the incident photons?

Solution: Here: W₀ = 4.2 eV; K.E_max = 2.6 eV

From Einstein’s photoelectric equation;

Energy of the incident photon, E = work function + maximum K.E. of emitted photoelectron

I.e.   E = W₀ + K.E_max = (4.2 + 2.6) eV = 6.8 eV

It means 6.8 eV energy is to be spent to remove one of the least tightly bound electrons from a metal surface.

When ultraviolet photons of a single frequency strike a metal, electrons with kinetic energies from 0 to 2.6 eV will be ejected.