The number of photo electrons emitted for light of a frequency v (higher than the threshold frequency v₀) is proportional to:

The correct answer is option 2) i.e. Intensity of light.

CONCEPT:

• Photoelectric effect: The photoelectric effect is a phenomenon where electrons are ejected from a metal surface when the light of sufficient frequency is incident on it.
  • ​Einstein suggested that light behaved like a particle and that each particle of light had energy called the photon.
  • When a photon falls on the metal surface, the photon’s energy is transferred to the electron.
  • Some part of the energy gets utilized in removing the electron from the metal surface, and the remaining goes into giving kinetic energy for the ejected electron.

Therefore, the total energy of photon = energy utilized to eject an electron + maximum kinetic energy of the electron. This is given by the equation:

E = W + EK

​Where E is the energy of the photon, W is the minimum energy required to emit an electron, and KE is the maximum kinetic energy achieved by the ejected electron.

EXPLANATION:

• Electrons are ejected only when the light of frequency greater than the threshold frequency is incident on the metal surface.
• The intensity of light refers to the amount of photon energy per unit area. 
  • So, the greater the intensity of light more will be the number of photons, and as a result, more will be the number of ejected electrons.