Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): When the entire Young's double slit experiment apparatus is immersed in water, the angular fringe width decreases. Reason (R): The wavelength of light decreases when it enters a denser medium, and angular fringe width is directly proportional to the wavelength. In the light of the above statements,

Step-by-step solution

The angular fringe width in Young's double slit experiment is given by = d , where is the wavelength of light and d is the distance between the slits. When the apparatus is immersed in water (a denser medium), the wavelength of light decreases to ' = , where is the refractive index of water. Since the angular fringe width is directly proportional to the wavelength ( ), a decrease in wavelength results in a decrease in the angular fringe width. Therefore, the Assertion is correct. The Reason correctly states that wa