Problem 5.103

A plane light wave with wavelength $\lambda=0.60 \mu \mathrm{m}$ falls normally on a sufficiently large glass plate having a round recess on the opposite side (Fig. 5.21 ). For the observation point $P$ that recess corresponds to the first one and a half Fresnel zones. Find the depth $h$ of the recess at which the intensity of light at the point $P$ is (a) maximum; (b) minimum; (c) equal to the intensity of incident light.