Question

Mention any three features of results of experiment on photoelectric effect which cannot be explained using the wave theory of light.

Answer 1

Here are three key experimental results that could not be explained by the wave theory:

1. Instantaneous Emission of Photoelectrons: No matter how weak the light source is, electrons are released as soon as light hits the metal surface. Wave theory states that energy should be absorbed progressively over time, delaying electron emission. This is not the case.
2. Existence of a Threshold Frequency: Regardless of light intensity, photoelectrons are only released when the light frequency (f) is higher than a specific threshold frequency (f₀). According to wave theory, even at low frequencies, a higher intensity (brighter light) should always give enough energy for electrons to escape. Wave theory is contradicted by the fact that no electrons are released below f₀.
3. Kinetic Energy of Electrons Depends on Frequency, Not Intensity: As it does not change with intensity, the maximum kinetic energy of released electrons rises with light frequency. Wave theory implies that increased light intensity should enhance energy transfer to electrons, increasing their kinetic energy. Instead, only higher frequencies result in more kinetic energy.