Question

The width of the fringes obtained with light of wavelength $2 \times 10^{-7}\text{ m}$ is $82\text{ mm}$. If the entire apparatus is immersed in a liquid of refractive index $3$, what will be the width of the resulting fringes?

• A. $1.82\text{ mm}$
• B. $0.71\text{ mm}$
• C. $2.8\text{ mm}$
• D. $1.4\text{ mm}$

Hint:

The initial wavelength value ($6.2 \times 10^{-7}\text{ m}$) is extra information provided to look complicated. Since fringe width scales inversely with the refractive index ($\beta' = \frac{\beta}{\mu}$), you only need to divide the initial width by the index value to get the answer.

Answer 1

The Correct Option is D