Point out two distinct features observed experimentally in photolelectric effect which cannot be explained on the basis of wave theory of light. State how the 'photon picture' of light provides an explanation of these features.

Explanation

### Step-by-Step Solution

1. **Identify the Two Distinct Features of the Photoelectric Effect:**
- The first feature is that the **maximum kinetic energy** of the emitted photoelectrons is **independent of the intensity** of the incident light.
- The second feature is that there is **no emission of photoelectrons** if the frequency of the incident light is **less than** or **greater than** the threshold frequency.

2. **Explain the First Feature:**
- According to wave theory, increasing the intensity of light should increase the energy delivered to the electrons, thus increasing their kinetic energy. However, in the photoelectric effect, even if the intensity of the light is increased, the maximum kinetic energy of the emitted electrons remains constant and is determined only by the frequency of the light. This indicates that the energy of the emitted electrons is not dependent on the intensity but rather on the frequency of the incident light.
...