Question

The intensity of light depends on:

• A. amplitude
• B. frequency
• C. wavelength
• D. none of the above

Answer 1

The correct option is A

amplitude

Explanation for correct option:
Option A:

1. Amplitude: The amplitude of a wave is the maximum distance moved by it on either side of the mean position.
2. Intensity: The intensity of light can be defined as the energy that is transmitted per unit area in one unit of time.
3. According to the electromagnetic theory, the intensity of a wave is directly proportional to its amplitude, i.e., $I\propto A^2$.
4. Since light is also an electromagnetic wave, the intensity of light will depend upon the amplitude of the wave.

Explanation for incorrect options:
Option B:

A change in frequency means the energy of photons is changing but not the brightness. So, the frequency has no effect on the intensity of light.

Option C:

A change in wavelength causes a change in energy of photons, but not in the intensity of the light.

Thus, the correct answer is option A.