Question

In Young’s experiment, light of wavelength 4000 Å is used, and fringes are formed at 2 metre distance and has a fringe width of 0.6 mm. If whole of the experiment is performed in a liquid of refractive index 1.5, then width of fringe will be

• A. 0.2 mm
• B. 0.3 mm
• C. 0.4 mm
• D. 1.2 mm

Answer 1

Answer: (C)

0.4 mm

Answer 2

$\beta_{medium} = \frac{\beta_{air}}{\mu}$ ⇒ $\beta_{medium} = \frac{0.6}{1.5} = 0.4mm$.