The refractive index is 1.333. At what angle to the normal must a beam of light be incident on the surface of

be incident on the surface of water for the refractive light to be plane polarised?
help is appreciated!
it'd be really nice to get an explanation as well because i'm a little confused

This can be worked out using Brewster's law stated as under.
"When a ray reflected from a surface of transparent object is totally plane polarized, the tangent of the angle of incidence (angle of polarization) is equal to the refractive index of the material of the object."
=> tan θp = 1.333
=> θp = arctan (1.333) = 53.12°.

You probably need another angle? Like of the refracted ray.
cause n= sin i / sin r
So you have n, if have sin r then you can find out sin i using substitution

(Do you have a diagram maybe you have to measure it?)