Deduce a relation between polarising angle and critical angle.

Explanation

According to Brewster's law,
`mu = tan i_(p)` [where `i_(p)` = polarising angle]
Again, according to Snell's law
`mu = (1)/(sin theta_(c )) `[where `theta_(c )` = critical angle]
`therefore " " tan i_(p) = (1)/(sin theta_( c)) or , tan i_(p) = "cosec" theta_( c)`
or,` " " i_(p) = tan^(-1) ("cosec" theta_(c))`
This is the required relation.