Question

Why can't the photoelectric effect be explained by the wave model?

Answer 1

Photoelectric effect:

1. When a substance absorbs light, electrically charged particles are emitted from it, resulting in the photoelectric effect.
2. The effect is frequently characterized as the ejection of electrons from a metal plate when exposed to light.

Threshold frequency:

1. The maximum kinetic energy of the photoelectrons is independent of the intensity of radiation and a minimum frequency is required for the photoelectric effect.
2. This minimum frequency is known as the threshold frequency.

The photoelectric effect cannot be described by wave theory for the following reasons:

1. Electrons are released after a tiny instant of time when light strikes a material, according to wave theory.
2. However, in the photoelectric effect, electron emissions occur immediately and without delay.
3. The energy of a wave grows as its intensity increases.
4. In the photoelectronic effect, however, increasing the intensity has no influence on the energy of electrons released.
5. All that occurs is an increase in the number of electrons expelled.

Dependence of current on intensity:

1. The current is directly proportional to intensity.
2. The current on the current-voltage graph increases as the values of intensities increase.
3. The graphical representation of the variation of current with the intensity of light when the frequency of the incident light is greater than the threshold frequency.