Problem 5.114

A plane light wave with wavelength $\lambda=0.65 \mu \mathrm{m}$ falls normally on a large glass plate whose opposite side has a long rectangular recess 0.60 mm wide. Using Fig. 5.19 , find the depth $h$ of the recess at which the diffraction pattern on the screen $77 \mathrm{~cm}$ away from the plate has the maximum illuminance at its centre.