Question

Two Polaroids P₁ and P₂ are placed with their axis perpendicular to each other. Unpolarised light I₀ is incident on P₁. A third polaroid P₃ is kept in between P₁ and P₂ such that its axis makes an angle 45⁰ with that P₁. The intensity of transmitted light through P₂ is:

• A. $\frac{I_0}{16}$
• B. $\frac{I_0}{2}$
• C. $\frac{I_0}{4}$
• D. $\frac{I_0}{8}$

Answer 1

The correct option is D

$\frac{I_0}{8}$

Light Intensity.

The brightness or quantity of light produced by a particular lighting source is referred to as the light's intensity.

Step 1:Given Data.

Two Polaroids P₁ and P₂ are placed with their axis perpendicular to each other.

Unpolarised light I₀ is incident on P₁.

A third polaroid P₃ is kept in between P₁ and P₂ such that its axis makes an angle 45⁰ with that P₁.

Step 2: Calculations.

Initial intensity = I ₀

After $P_1\to I_1=\frac{I_0}{2}$

After $P_3\to I_2=I_1{\cos }^2{45}^0$

$I_2=\frac{I_0}{2}x\frac{1}{2}$

We get,

$I_2=\frac{I_0}{4}$

After$P_2\to I_3=I_2{\cos }^2{45}^0$

$I_3=\frac{I_0}{4}x\frac{1}{2}$

we get,

$I_3=\frac{I_0}{8}$

Hence, the intensity of transmitted light through P₂ is$\frac{I_0}{8}$

So, the correct option is (D)