Question

In a Young's double-slit experiment, the screen is moved away from the plane of the slits. What will be its effect on the following ? (i) Angular separation of the fringes. (ii) Fringe-width.

The British physicist Thomas Young explained the interference of light using the principle of superposition of waves. He observed the interference pattern on the screen, in his experimental set-up, known now as Young's double slit experiment. The two slits S₁ and S₂ were illuminated by light from a slit S. The interference pattern consists of dark and bright bands of light. Such bands are called fringes. The distance between two consecutive bright and dark fringes is called fringe width.

In a Young's double slit experiment using light of wavelength 600 nm, the slit separation is 0.8 mm and the screen is kept 1.6 m from the plane of the slits. Calculate:

In a Young's double slit experimental set-up, the intensity of the light waves from two coherent sources are in the ratio of 4 : 9. Find the ratio of intensity of bright and dark fringes in the interference pattern.