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 is true and R is true and R is the correct explanation of A.
B. A and R are true but R is not correct explanation of A
C. A is true, R is false
D. A is false, R is true.

Answer

C

Explanation

`beta = (lambda D)/(d) implies beta prop lambda [mu prop (1)/(lambda)]`
`mu_(omega)gt mu_("air")` hence `lambda_(omega)lt lambda_("air")` thus `beta_(omega)lt beta_("air")`
A is true and R is false.