Question

Two polaroids P₁ and P₂ are placed with their pass axes perpendicular to each other. An unpolarised light of intensity I₀ is incident on P₁. A third polaroid P₃ is kept in between P₁ and P₂ such that its pass axis makes an angle of 30° with that of P₁. Determine the intensity of light transmitted through P₁, P₂ and P₃

Answer 1

As given in the question, the polaroids P₁ and P₂ are placed with their pass axes perpendicular to each other. Also, polaroid P₃ is placed at an angle of 30° with respect to P₁.

Now, we have:

Intensity of light after falling on P₁ `I'=I_0/2`

Intensity of light after falling on P_3, I" = 

`I'cos^2(theta)=I_0/2cos^2(30^@)=(3I_0)/8`

Therefore, a light of intensity `(3I_0)/8`will pass through the P₃, and the angle between P₃ and P₂ will be 60° because of the condition given in the question.

Intensity of light after falling on P_2, I"' = I" `cos^2(theta)=(3I_0)/8cos^2(60^@)=(3I_0)/32`