Question

(a) At what angle above the horizontal is the sun if sunlight reflected from the surface of a calm lake is completely polarized? (b) What is the plane of the electric-field vector in the reflected light?

Short answer

1. The angle above the horizontal is
2. The plane is perpendicular to the incident light plane, which is the horizontal plane.

Step-by-step solution

Brewster’s law

Brewster’s law for polarising angle;

Here,

Angle above the horizontal

Medium${\mathrm{n}}_1$is air

Medium${\mathrm{n}}_2$for water RI is 1.33

(a) So, the angle is;

Plane of the electric-field vector in the reflected light

(b) Hence, the plane is perpendicular to the incident light plane, which is the horizontal plane.