Question

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R  
Assertion A: The phase difference of two light waves change if they travel through different media having same thickness, but different indices of refraction.  
Reason R: The wavelengths of waves are different in different media.  
In the light of the above statements, choose the most appropriate answer from the options given below 

• A. Both A and R are correct and R is the correct explanation of A
• B. Both A and R are correct but R is NOT the correct explanation of A
• C. A is correct but R is not correct
• D. A is not correct but R is correct

Answer 1

The Correct Option is A

As we know the speed of light in a medium: \[ v = \frac{c}{\mu} \quad \text{or} \quad f \lambda = \frac{c}{\mu} \] Therefore, \(\lambda \propto \frac{1}{\mu}\).
When light travels through two different mediums, their phase difference will change: \[ \Delta Q = \frac{2\pi}{\lambda} \] Thus, statement R is the correct explanation of A.