Young's Double Slit Experiment: Practice Problem & Solution

Short Solution (Best for NEET):

To solve this problem, we apply the core principles of Young's Double Slit Experiment. Understanding the underlying formula is key to arriving at the correct answer below:

Fringe width in a medium of refractive index $\mu$ is $\beta' = \frac{\beta}{\mu}$. Given $\beta = 0.4 mm$ and $\mu = 4/3$, the new fringe width is $\beta' = \frac{0.4}{4/3} = 0.30 mm$.