Question

Two polaroids are placed at 90° to each other and the transmitted intensity is zero. What happens when one more polaroid is placed between these two bisecting the angle between them? What will be the direction of polarization of outcoming beam?

Answer 1

Answer:

Explanation:

If ordinary unpolarised light of intensity Iº' is incident on first Polaroid (A,say),

intensity of light transmitted from first polaroid is Io=Io'/2

Given angle between transmission axes of two polaroids A and B is initially 90º.

According to Malus law, intensity of light transmitted from second polaroid (B, say) is

I =Io cos2  = I = Io cos290º = 0

When one more polaroid (C say) is placed between A and B making an angle of 45º with the transmission axis of either of polaroids, then intensity of light transmitted from A is Ia Io/2=Io/2