Question

in a stack of 3 polarising sheets ,the first ans the third are crossed while middle one has its axis 45 degree to the axes of the other two .fraction of intensity of an incident unpolarised beam of light that is transmitted by stack is what

Answer 1

Given :

Polarizing sheets = 3

Angle between first and third polarizer = 90°

Angle between first and second polarizer = 45°

To Find :

Fraction of intensity of incident unpolarized light transmitted by stack

Solution :

The intensity is halved as an unpolarized light passes through a polarizer.

Thus, according to the Malus Law -

Ifinal/I0

= I0/2 x cos²45° x cos²45°/ I0

On solving we will get -

I = I0/8

Answer: The  fraction of intensity of beam after coming the stack of three polarizers will be 1/8.