Question

When a mica sheet of thickness 7 microns and μ=1.6 is placed in the path of one of interfering beams in a biprism experiment then the central fringe gets at the position of seventh bright fringe. The wavelength of light used will be

• A. 4000 \AA
• B. 5000 \AA
• C. 6000 \AA
• D. 7000 \AA

Hint:

Mica sheet introduces an optical path difference.

Answer 1

The Correct Option is B

Shift in fringe, n=((μ-1)t)/(λ) 7=(1.6-1)×7×10⁻⁶λ λ=5×10⁻⁷ m=5000