Question

Intensity of light depends on
A. Amplitude
B. Frequency
C. Wavelength
D. Velocity

Answer 1

.To solve the given question, we must know about the intensity of a wave because light is also a wave. Find out on what factor that the intensity of a wave depends and relate it to the light.

Complete step by step answer:
Let us first understand what intensity of light is.
Intensity of light is defined as the energy transmitted per unit area in one unit of time.
Suppose a source of light is in the form of a spherical shape and it is emitting a light of some wavelength. Then the intensity of the light at the surface of the spherical source is equal to the energy emitted by it per unit time through a unit area of its surface.
From electromagnetic theory we know that light is a wave. And intensity of a wave is directly proportional to the amplitude of the wave.
i.e. $I\propto {{A}^{2}}$, where I is intensity and A is amplitude of the wave.
This means that the intensity of a wave depends on the amplitude of the wave. Since light is also a wave, its intensity will depend on the amplitude of the wave.

So, the correct answer is “Option A”.

Note:
The frequency of the light influences the energy per photon. The energy per photon is given as $E=hf$ …. (i),
where h is Planck’s constant and f is the frequency of the light.
The frequency and wavelength of the light are related as $f\lambda =v$,
where $\lambda$ is the wavelength of the light and v is its velocity.
$\Rightarrow f=\dfrac{v}{\lambda }$.
Substitute the value of f in (i).
$\Rightarrow E=h\dfrac{v}{\lambda }$.
This means that the energy per photon of the light depends on its wavelength and velocity.