Question

Two polaroids P₁ and P₂ are placed with their pass axes perpendicular to each other. An unpolarised light of intensity I_o is incident on P₁. A third polaroid P₃ is kept in between P₁ and P₂ such that its pass axis makes an angle of 45° 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, P₃ is placed at an angle of 45° with respect to P₁.

Now, we have:

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

Intensity of light after falling on P₃ I"=

`I'cos^2(theta)=I_0/2cos^2(45^@)=I_0/4`

Therefore, a light of intensity `I_0/4`will pass through P₃ and the angle between P₃ and P₂ will be 45° because of the condition given in the question.

Intensity of light after falling on P₂ I''' = I'' `cos^2(theta)=I_0/4cos^2(45^@)=I_0/8`