Question

Distinguish between polarized and unpolarized light. Does the intensity of polarized light emitted by a polaroid depend on its orientation? Explain briefly.
The vibration in a beam of polarized light make an angle of 60° with the axis of the polaroid sheet. What percentage of light is transmitted through the sheet?

Answer 1

Unpolarized light are those light waves whose planes of vibrations are randomly oriented about the direction of propagation of the wave.
Polarized light waves are those light waves in which planes of vibrations can occur in one particular plane only.

Yes, the intensity of polarized light emitted by a polaroid depends on its orientation. When polarized light is incident on a polaroid, the resultant intensity of light transmitted from varies directly as the square of the cosine of the angle between polarization direction of light and axis of the polaroid.
The intensity of light transmitted can be given using Malus law as

\[I = I_0 \cos^2 \theta = I_0 \cos^2 60\text{degree} = \frac{I_0}{4}\]

Percentage of light is transmitted through the polaroid sheet is = 

\[\frac{I_0 - \frac{I_0}{4}}{I_0} \times 100 = 75 %\]