(a) Suppose that an ordinary light is incident normally on a pair C1 and C2. When the incident ray of light passes through crystal C1, it gets plane polarised in the direction perpendicular to the length of the crystal. Now we see that when the axis of two crytal are parallel, the intensity of the merging light will be maximum. When the second crystal is placed perpendicular with respect to the first crystal, the intensity of light observed is zero. This is done to the electric field of the plane polarised light obtained from the C1 can only vibrate only in one direction.
This shows the traverse nature of light.
(b) Given: -
The intensity of the incident light I0
After passing the first polaroid (P1) the intensity be I1
We know that I1 reduces to half
After passing the third polaroid (P3) the intensity be I2
We can write by malus’ law as,
Here, is given 30o,
Also, the angle between the pass axis of P3 and P2 is 600,
Therefore a light of the intensity I2 will pass through P3 And the angel between the P3 and P2
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