Question 9: Use photon model to explain why ultraviolet is harmful to your skin while visible light is not?
The harmfulness of radiation depends upon the energy of the radiation. Radiations having more energy penetrate deeper in the tissues and are more likely to disrupt the chemical structure of the cells.
Energy of the photon is given by, E = hf. Here h is the Planck’s constant and f is the frequency of the photon. Now we know that the frequency of ultraviolet radiation is much greater than the frequency of the radiations in the visible region. Therefore, photons of ultraviolet radiation penetrate deeper in the human body and may cause damage to the living tissues. On the other hand, frequency of the visible radiations is not harmful to that extent.