Question

Photons of energy 7.0 eV strike a metal whose work function is 2.3 eV. KE of the most energetic photoelectron is

5.2 eV
3.8 eV
4.7 eV
7.4 eV
9.3 eV

Answer 1

It is 4.7 eV.

Step-by-step explanation:

According to the photo electric equation

Energy = Work function + Kinetic energy

Where, Work function is defined as the minimum energy required to remove the photo electron from the metal surface.

Here, Energy = 7.0 eV, Work function = 2.3 eV

So, kinetic energy = Energy - Work function

Kinetic energy = 7.0 eV - 2.3 eV = 4.7 eV

Answer 2

The kinetic energy of the most energetic photoelectron is 4.7 eV. This was obtained by subtracting the energy of the photon that excited that electron from its work function. By doing this, the excess energy is equal to the kinetic energy of the photoelectron.