Assertion (A) : If the whole apparatus of YDSE is immersed in a liquid, then the fringe width will decrease
Reason (R ) : The wavelength of light in water is more than that of air.

Options

A. (a) If both assertion and reason are true and reason is the correct explanation of assertion.
B. (b) If both assertion and reason are true but reason is not the correct explanation of assertion.
C. (c) If assertion is true but reason is false.
D. (d) If assertion and reason both are false.

Answer

C

Explanation

When whole of the apparatus is immered in water, then wavelength of light decreases from the relation
`lambda^'=lambda//mu`, `mu` being refractive index of water.
Therefore, fringe with (`beta=(Dlambda)/(d)` or `betaproplambda`) will decrease as `lambda` decreases when immersed in water.
Also we conclude that wavelength of light in water is less than that in air.