All Problems Diffraction of Light
Problem 5.100
A plane monochromatic light wave with intensity \(I_{0}\) falls normally on an opaque screen with a round a perture. What is the intensity of light \(I\) behind the screen at the point for which the aperture (a) is equal to the first Fresnel zone; to the internal half of the first zone; (b) was made equal to the first Fresnel zone and then half of it was closed (along the diameter)?
(a) \(I^{2} \approx 4 I_{0}, I \approx 2 I_{0}\) (b) \(I \approx I_{0}\)