In photoelectric effect, why should the photoelectric current increase as the intensity of monochromatic radiation incident on a photosensitive surface is increased? Explain.

In the photoelectric effect, the photoelectric current is the flow of electrons emitted from a photosensitive surface when it is illuminated by light. The intensity of monochromatic radiation refers to the amount of light energy incident per unit area per unit time. When the intensity of monochromatic radiation incident on a photosensitive surface is increased, several factors contribute to an increase in the photoelectric current:

1. Greater Number of Photons: Increasing the intensity of monochromatic radiation means that there are more photons striking the photosensitive surface per unit time. Each photon has a certain amount of energy associated with it. With a higher intensity, there are more photons available to interact with the surface, leading to a greater number of photoelectric emissions.

2. More Electrons Emitted: Each photon that interacts with the photosensitive surface has the potential to eject an electron if its energy exceeds the work function of the material. With higher intensity, more photons possess sufficient energy to overcome the work function and eject electrons from the surface. Therefore, increasing the intensity results in more electrons being emitted, leading to a higher photoelectric current.

3. Greater Electron Kinetic Energy: As the intensity increases, the number of ejected electrons per unit time also increases. These emitted electrons typically have a range of kinetic energies, depending on the energy of the incident photons. With higher intensity, there is a greater chance of higher-energy photons interacting with the surface, resulting in electrons being emitted with higher kinetic energies. This contributes to an overall increase in the photoelectric current.

4. Saturated Current: In certain cases, there may be a limit to the increase in photoelectric current with increasing intensity. This is because the photoelectric current can reach a saturation point, where further increases in intensity do not lead to a proportional increase in the number of emitted electrons. At this point, all available electrons in the material have been emitted, and the photoelectric current reaches a maximum value.

Overall, increasing the intensity of monochromatic radiation incident on a photosensitive surface increases the number of photons interacting with the surface, leading to more electrons being ejected and a higher photoelectric current.