Question

Interference was observed in an interference chamber when air was present. Now, the chamber is evacuated and if the same light is used, a careful observation will show(a) no interference(b) interference with bright bands(c) interference with dark bands(d) interference in which breadth of the fringe will be slightly increased

Answer 1

Answer:

Explanation:

Fringe Width is denoted as - β = λD/d

The refractive index of air is slightly more than 1 and in vaccum, it increases very slightly as compared to that in air. Thus, when the chamber is evacuated, the overall refractive index decreases and hence the wavelength increases. As β is proportional to wavelength, therefore, width of interference fringe increases slightly, with an additional increase in the fringe width.