Physics - Wave Optics Question with Solution | TestHub

Intensity of the incident unpolarized light is $I_0$.

When unpolarized light passes through the first polaroid, the intensity of the transmitted light becomes half of the incident intensity:

$I_1=\frac{I_0}{2}$

The second polaroid is placed such that its transmission axis is at an angle of $60^{\circ }$ with respect to the first polaroid. According to Malus's law, the intensity of light transmitted through the second polaroid is:

$I_2=I_1{\cos }^2(60^{\circ })=\frac{I_0}{2}\times {\left(\frac{1}{2}\right)}^2=\frac{I_0}{2}\times \frac{1}{4}=\frac{I_0}{8}$

The third polaroid is placed such that its transmission axis is at an angle of $60^{\circ }$ with respect to the second polaroid. The intensity of light transmitted through the third polaroid is:

$I_3=I_2{\cos }^2(60^{\circ })=\frac{I_0}{8}\times {\left(\frac{1}{2}\right)}^2=\frac{I_0}{8}\times \frac{1}{4}=\frac{I_0}{32}$

The fraction of the incident light intensity that passes through the system is:

$\frac{I_3}{I_0}=\frac{1}{32}$

Answer: $\frac{1}{32}$