Question 246: Wave Optics

Question

Two polaroids are oriented with their planes perpendicular to incident light and transmission axis making an angle $30^{\circ}$ with each other. What fraction of incident unpolarised light is transmitted?
$$ \left(\cos 30^{\circ}=\sqrt{3} / 2\right) $$

Accepted Answer

For unpolarised light passing through two polaroids at angle $	heta=30^{\circ}$ :
$$ I=I_0 \cos ^2 	heta $$
After passing through the first polaroid,
$$ \mathrm{I}_1=\frac{\mathrm{I}_0}{2} $$
After passing through the second polaroid,
$$ I_2=I_1 \cos ^2 30^{\circ}=\frac{I_0}{2} \cdot\left(\frac{\sqrt{3}}{2}ight)^2=\frac{I_0}{2} \cdot \frac{3}{4}=\frac{3 I_0}{8} $$
$	herefore \quad$ Transmitted fraction is $37.5 \%$

Answer

$57.5 \%$

Answer

$17.5 \%$

Answer

$27.5 \%$

Answer

$37.5 \%$

Wave Optics

Two polaroids are oriented with their planes perpendicular to incident light and transmission axis making an angle 30^{\circ} with each other. What fraction of incident unpolarised light is transmitted? $ \left(\cos 30^{\circ}=\sqrt{3} / 2\right)

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