Question

In Young’s double slit experiment performed in air medium, the fringe width observed is 1.4 mm. If the entire arrangement is kept in a liquid medium of refractive index 1.4, then the fringe width (in mm) will be

• A. 1.4
• B. 1.0
• C. 0.7
• D. 2.8
• E. 0.5

Hint:

Fringe width decreases in medium: \(\beta \propto \frac{1}{\mu}\).

Answer 1

The Correct Option is B

Concept: \[ \beta = \frac{\lambda D}{d} \]

Step 1: Effect of medium.
\[ \lambda' = \frac{\lambda}{\mu} \]

Step 2: New fringe width.
\[ \beta' = \frac{\beta}{\mu} = \frac{1.4}{1.4} = 1.0\, \text{mm} \]