Question

Answer the following giving reason:
(a) All the photoelectrons do not eject with the same kinetic energy when monochromatic light is incident on a metal surface.
(b) The saturation current in case (a) is different for different intensity.
(c) If one goes on increasing the wavelength of light incident on a metal sur face, keeping its intensity constant, emission of photoelectrons stops at a certain wavelength for this metal.

Hint:

The photoelectric effect depends on the frequency of light and the work function of the material. Intensity increases the number of photoelectrons, while wavelength controls whether electrons are emitted.

Answer 1

% Option (a) The photoelectrons do not eject with the same kinetic energy because the energy of each photoelectron depends on both the energy of the incoming photon and the work function of the metal. The kinetic energy of a photoelectron is given by: \[ K.E. = h\nu - \phi \] where \( h\nu \) is the energy of the photon and \( \phi \) is the work function of the metal. Different photons may have different energies, and the photoelectrons will have varying kinetic energies. % Option (b) The saturation current depends on the intensity of the light because intensity is proportional to the number of photons incident on the surface. A higher intensity results in more photoelectrons being emitted, thus increasing the saturation current. % Option (c) When the wavelength of the light increases, the energy of the photons decreases, and eventually, if the wavelength becomes too long, the energy of the photons becomes less than the work function \( \phi \) of the metal. At this point, no photoelectrons are ejected, and the emission stops.