Explanation of the laws of photoelectric emission using quantum theory

The quantum theory states that “light is emitted and absorbed in discrete packets of energy called photons”

i.e. E = hf

When light is incident on a metal surface, each photon interacts with a single electron giving it all its energy. The photon is absorbed if its energy is greater than the work function and if it is less, the photon is rejected.

Increasing the intensity of light increases the number of photons striking the metal surface per second. Therefore more electrons are emitted per second and the photocurrent increases with intensity.

Increasing the frequency of incident radiation increases the energy of each photon and therefore the maximum kinetic energy of the liberated electrons increases with the frequency of radiation.

Increasing the intensity of light only increases the number of photons but not the energy in each photon. Hence kinetic energy of the emitted electrons is independent of the intensity of the incident radiation

i.e. K.E = hf + w₀ where K.E = kinetic energy of emitted electron, h = Plank’s constant, f = frequency of the radiation, w₀ = work function (minimum energy required to dislodge an electron from a material)

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Dr. Bbosa Science