Question

If young's double-slit experiment is performed in water instead of air, then

• A. No fringes would be seen
• B. Fringe width would decrease
• C. Fringe width would increase
• D. Fringe width would remain unchanged

Answer 1

The correct option is B

Fringe width would decrease

The behavior of light in water:

1. Water is a denser medium for light to travel compared to air.
2. The frequency of the light remains unchanged.
3. The wavelength of the light decreases in denser mediums.

The explanation for the Correct answer:

option B: Fringe width would decrease

1. The formula for fringe width is $Y=\frac{\lambda D}{d}$ where $\lambda$ is the wavelength, $D$ is the distance between source and screen and $d$ is the distance between slits.
2. As the wavelength $\lambda$ is decreased fringe width also decreases.
3. Hence, option B is correct.

Explanation of the incorrect answer(s):

Option A: No fringes would be seen

1. Fringes will be formed as the frequency of the light is not changed.
2. Hence, option A is incorrect.

Option C: Fringe width would increase

1. It is clear from option B that fringe width will decrease
2. Hence, option C is incorrect.

Option D: Fringe width would remain unchanged

1. It is clear from option B that fringe width will decrease.
2. Hence, option D is incorrect.

Hence, option B is the correct answer.