Задача id13686

A lens with a focal length F = 50 cm and a diameter D = 5 cm is illuminated by a parallel monochromatic beam of light with a wavelength l = 630 nm. Find how many times the intensity of wave I at the focus of the lens exceeds the intensity of wave I0 incident on the lens. Estimate the size b of the spot in the focal plane.

Answer. Format gif