A plane monochromatic light wave falls normally on an opaque half-plane. A screen is located at a distance b = 100 cm behind the half-plane. Making use of the Cornu spiral (Fig. 5.19), find:
(a) The ratio of intensities of the first maximum and the neighbouring minimum;
(b) The wavelength of light if the first two maxima are separated by a distance ∆x = 0.63 mm.