Question

Two monochromatic beams, one red and the other blue, have the same intensity. In which case (i) the number of photons per unit area per second is larger, (ii) the maximum kinetic energy of the photoelectrons is more? Justify your answer.

Answer 1

(i) Number of photons per unit per second in both the beams is same as they have the same intensity.

(ii) The maximum kinetic energy of photoelectrons is given by

E=hν−ϕw

hereh=Planck's constant

ν=Frequency of incident light

ϕ=Workfunction of the material

We know that the frequency of blue beam is more than that of red beam. So, from the equation of maximum kinetic energy, we can say that the maximum kinetic energy of the photoelectrons of the blue beam will be more