In a double slit experiment the angular width of a fringe is found to be `0.2^(@)` on a screen placed I m away. The wavelength of light used in 600 nm. What will be the angular width of the fringe if the entire experimental apparatus is immersed in water ? Take refractive index of water to be `4//3`.

Explanation

To solve the problem, we will follow these steps:

### Step 1: Understand the relationship between fringe width and wavelength
In a double-slit experiment, the angular width of the fringe (θ) is given by the formula:
\[ \theta = \frac{\lambda}{d} \]
where:
...