Unpolarised light is incident on a plane glass surface. What would be the angle of incidence so that the reflected and refracted rays are perpendicular to each other.

Explanation

Here, reflected and refracted light rays are given perpendicular and so angle of incidence (1) must be equal to polarising angle or Brewster angle shown by symbol `theta_(p)`. Now, according to Brewsters. law,
`tantheta_(P)=mu`
`:.tantheta_(P)=1.5`
`("":."Here "mu-mu_(ga)-(mu_(g))/(mu_(a))=(1.5)/(1)=1.5)`
But `tan(56^(@)19.)=1.5003~~1.5`
`impliestheta_(P)=56^(@)19.`
Note: Here if `theta_(P)` is required only in degree then
`theta_(P)=56^(@)+19.=56^(@)+((19)/(60))^(@)`
`=56^(@)+(0.32)^(@)`
`=(56.32)^(@)`