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 principa - Physics MCQ JEE Main 2026 | ExamTest.live

mediumMCQJEE Main2026Physics

1 mark

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 the emergent light is:

Solution & Step-by-step Explanation

1. When unpolarised light passes through the first polaroid (A), its intensity is halved: I_{A} = \frac{I _{0}}{2} .2. This light is now polarized. When it passes through the second polaroid (B), we use Malus's Law: I_{B} = I_{A} cos^{2} θ I_{B} = (\frac{I _{0}}{2}) cos^{2} (4 5^{\circ}) = (\frac{I _{0}}{2}) (\frac{1}{2})^{2} = \frac{I _{0}}{2} \times \frac{1}{2} = \frac{I _{0}}{4} .

Try it yourself before checking the explanation above.

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 the emergent light is:

I_0/2

I_0/4

I_0/8

I_0

Practice with timed mock tests and track your performance across Physics.