Question

' $n$ ' polarizing sheets are arranged such that each makes an angle $45^{\circ}$ with the preceeding sheet An unpolarized light of intensity I is incident into this arrangement The output intensity is found to be $I / 64$ The value of $n$ will be:

• A. 6
• B. 5
• C. 3
• D. 4

Answer 1

Answer: (A)

6

Answer 2

After passing through the first sheet
$I_1=\frac{I}{2}$
After passing through the second sheet
$I_2 = I_1\text{ }cos^{2}(45\degree)= \frac{I}{4}$
After passing through nth sheet
$I_n=\frac{I}{2^n}=\frac{I}{64}$
$n=6$