solve and explain a with diagram.

We use Malus' Law.

Since the unpolarized light nearly consists of 50% light polarized parallel to the principal axis and 50% perpendicular to it.

Hence from C the intensity will be 50% of incident.

While the polarized light coming out of C can similarly resolved into components parallel and perpendicular to the principal axis of prism B.

The parallel component being cos 45. And intensity is propotional to the square of amplitude.

Hence cos²45 = 1/2 of the intensity of polatized light from C.

Hence the intensity from B is (1/2)(1/2) = 1/4 = 0.25 i.e. 25% of the unpolarized light.

Regards,

Team,

TopperLearning.