Polarization at reflection Brewsters law

If natural light falls on the border surface of two media the reflected and refracted beams are partly polarized. This occurs because of the fact that from a dielectric surface only the component of the E vector which is parallel to the border surface (perpendicular to the incidence plane) is reflected. Then, in the reflected light the oscillations perpendicular to the plane of incidence will predominate, whereas in the refracted beam the oscillations parallel to the plane of incidence will prevail. It has been experimentally established that when reflected from a dielectric snrface light is completely polarized if there is a certain relationship between the incidence angle a and the refraction index  

Here the angle is referred to as the Brewster angle and the given reflection is known as Brewster s law. However, the refracted beam is polarized only in part. 

Solution According to Brewster s law, when reflected from a dielectric light is completely polarized if the tangent of the incidence angle is equal to tan 8i = ( 2/ i) = 2i where 2i is the relative index of the second body (glass) relative the first (liquid). The relative refractive index 2i is the ratio of absolute indexes, i.e tan s 2 = ( 2/ i)- The reflected beam makes an angle of 2g = cp and, consequently, tan ((p/2) = ( 2/ i)- Therefore, i = 2/tan ((p/2) and the refraction index is 1.33. 

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