JEE Main · 2024 · 30 Jan 2024 · Shift 2 · Wave Optics

A beam of unpolarised light of intensity

I_{0}

is passed through a polaroid A and then through another polaroid B which is oriented so that its principal plane makes an angle of

4 5^{\circ}

relative to that of A. The intensity of emergent light is:

(A) $I_{0} /4$ ✓ Correct
(B) $I_{0}$
(C) $I_{0} /2$
(D) $I_{0} /8$

Answer: (A)

Solution

Unpolarised light of intensity

I_{0}

passing through polaroid A comes out with half the intensity:

I_{A} = \frac{I _{0}}{2}

This linearly polarised light then passes through polaroid B, whose axis is at

4 5^{\circ}

to A's. By Malus's law:

I_{B} = I_{A} cos^{2} 4 5^{\circ} = \frac{I _{0}}{2} \times \frac{1}{2} = \frac{I _{0}}{4}

JEE Main · 2024 · 30 Jan 2024 · Shift 2 · Single correct option

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