Question

A double slit experiment is immersed in water of refractive index \(1.33\). The slit separation is 1 mm, distance between slit and screen is \(1.33\) m. The slits are illuminated by light of wavelength 6300 \(\text{Å}\). The fringe width is

• A. \(4.9\times 10^{-4}\) m
• B. \(6.3\times 10^{-4}\) m
• C. \(8.6\times 10^{-4}\) m
• D. \(5.8\times 10^{-4}\) m

Hint:

Fringe width = lambda D / d with the wavelength in the medium lambda / n.

Answer 1

The Correct Option is B

Step 1: Wavelength in water
$\lambda_w = 6300/1.33$ angstrom.

Step 2: Fringe width
$\beta = \lambda_w D/d = \dfrac{(6300/1.33)\times10^{-10}\times1.33}{10^{-3}}$.

Step 3: Result
$6.3\times10^{-4}$ m. Option (B).

Final Answer:
Option (B). \[ \boxed{6.3\times10^{-4}\text{ m}} \]