Answer
a. $58.9^{\circ}$.
b. $51.2^{\circ}$.
Work Step by Step
a. The light strikes the glass at Brewster’s angle (the polarizing angle) because we know the reflected light is completely polarized.
Equation 33.8 tells us $tan \theta_p=\frac{n_b}{n_a}$.
$$tan \theta_p=\frac{1.66}{1.00}$$
$$\theta_p=58.9^{\circ}$$
b. Repeat, using water instead of air.
Equation 33.8 tells us $tan \theta_p=\frac{n_b}{n_a}$.
$$tan \theta_p=\frac{1.66}{1.333}$$
$$\theta_p=51.2^{\circ}$$
