Answer:
62.5 %
Explanation:
Let the initial intensity of unpolarized light is Io.
After first polariser the intensity of light becomes I'.
So, [tex]I' = \frac{I_{0}}{2}[/tex]
Now it passes through another polariser. The angle between the first polariser and the second polariser is given by Ф. The intensity is I''.
According to the law of Malus
[tex]I'' = I' Cos^{2}\phi[/tex]
Here, Ф = 30 degree
[tex]I'' = \frac{I_{0}}{2} Cos^{2}30=0.375I_{0}[/tex]
The percentage change in the intensity is given by
[tex]\frac{I_{0}-I''}{I_{0}}\times 100=\frac{I_{0}-0.375I_{0}}{I_{0}}\times100[/tex]
= 62.5 %
