Question:
The intensity of the transmitted light after passing through a first polaroid $P_1$ is $I_0$. If the second polaroid $P_2$ is rotated through an angle of $45^\circ$ with respect to $P_1$, then the change in the intensity of the transmitted light after passing through the second polaroid is
The intensity of the transmitted light after passing through a first polaroid $P_1$ is $I_0$. If the second polaroid $P_2$ is rotated through an angle of $45^\circ$ with respect to $P_1$, then the change in the intensity of the transmitted light after passing through the second polaroid is
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Malus law: intensity varies as $\cos^2\theta$.
Updated On: Apr 24, 2026
- $\frac{I_0}{2}$
- $\frac{I_0}{4}$
- $\frac{3I_0}{4}$
- $\frac{I_0}{3}$
- $\frac{3I_0}{2}$
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The Correct Option is A
Solution and Explanation
Concept:
• Malus law: \[ I = I_0 \cos^2\theta \]
Step 1: After second polaroid
\[ I = I_0 \cos^2 45^\circ = I_0 \times \frac{1}{2} \]
Step 2: Change in intensity
\[ \Delta I = I_0 - \frac{I_0}{2} = \frac{I_0}{2} \] Final Conclusion:
Option (A)
• Malus law: \[ I = I_0 \cos^2\theta \]
Step 1: After second polaroid
\[ I = I_0 \cos^2 45^\circ = I_0 \times \frac{1}{2} \]
Step 2: Change in intensity
\[ \Delta I = I_0 - \frac{I_0}{2} = \frac{I_0}{2} \] Final Conclusion:
Option (A)
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