Question

If Young's double slit experiment of light, interference is performed in water, which one of the following is correct?

• A. Fringe width will decrease
• B. Fringe width will increase
• C. There will be no fringe
• D. Fringe width will remain unchanged

Answer 1

Answer: (A)

Fringe width will decrease

If Young's double slit experiment is performed in water of refractive index μμ instead of air, the wavelength of light change from λλ to (λ/μ)(λ/μ)
∴β′=Dd(λμ)=βμ∴β′=Dd(λμ)=βμ
Fringe width reduces and becomes (1/μ)(1/μ) times of its value in air.