Question

Two Polaroids (polarizers that can polarize visible light) are aligned so that the light passing through them is a maximum. At what angle should one of them be placed so that the intensity is subsequently reduced by half?

Answer 1

Let the intensity of light from the first polaroid is I_o

The intensity through the second polaroid is,

`I=I_{\text{o}}\cos ^2(\theta)`

where,

`\theta\text{ is the angle between the }direction\text{ of polarisation of two polaroids,}`

For the angle,

`\theta=45^(\circ)`

The intensity of light from the second polaroid is,

`\begin{gathered} I=I_o\cos ^2(45^(\circ)) \\ I=I_(\circ)(\frac{1}{\sqrt[]{2}})^2 \\ I=(I_(\circ))/(2) \end{gathered}`

Thus, the intensity of light from the second polaroid becomes half if the angle between the direction of polarization of two polaroids is 45 degree.