Question

Interference was observed in interference chamber when air is present. Now, the chamber is evacuated and if the same light is used, then for the same arrangement:

• A. no interference pattern will be obtained
• B. exactly same interference pattern will be obtained with better contrast
• C. the fringe width is slightly decreased
• D. the fringe width is slightly increased

Answer 1

Answer: (A)

no interference pattern will be obtained

when the air is replaced with vaccum the wave length increases slightly so that the fringe spacing also inceases so the interference fringes cannot be formed