Reflectance and Transmittance of Light in Water-Glass Interface

[876d34f]

Homework Statement

There's a block of glass and it has a refractive index n = 1.5 and it is put in water.
Randomly polarized light is incident from the water towards the glass at an angle of 53 degrees to the normal.

a) what % p-polarized (part) of the em wave (light) is reflected off the glass? and the % of total incident power of the light is transmitted in the block?

Homework Equations

so my solution I guess is

The Attempt at a Solution

R% (reflectance) = Pr^2/Pi
Hence then if you find Pr , using Pr equation, and Pi but I don't know... how to find those
do I have to derive them?

 

[876d34f]

Okay, so I don't know how to proceed on this problem

I figure the randomly polarized light has 50% p-polarized and 50% s-polarized so I guess I would figure out the Brewster's Angle.

using

\tan(\Theta_{B})=\frac{n_{2}}{n_{1}}

which gives approximately 49 degrees

do I then use a Fresnel Equation? and then some how find the amount of p-polarized? and that happens to be out of 50 which then is out of 100%?