Physical Optics

In a double-slit experiment, the distance between slits is 5 mm and the slits are 1 m from the screen. Two interference patterns can be seen on the screen: one due to light of wavelength 480 nm, and the other due to light of wavelength 600 nm. What is the separation on the screen between the third-order bright fringes of two interference patterns?

Two sources of intensities 4I and I are used in an interference experiment. Obtain the intensities at points where the waves from two sources superimpose with a phase difference of (a) 0 (b) π/2 (c) π.

Define interference. What do you mean by coherent source of light? Derive necessary theory of interference due to wedge shape thin film.