A light ray enters from medium A to medium B as shown in the figure. The refractive index of medium B relative to A will be

Options

A. `(2 pi)/(n_(1)lamda_(1))(n_(3)-n_(2))t`
B. `(2pi)/(lamda_(1))(n_(3)-n_(2))t`
C. `(2pin_(1))/(n_(2)lamda_(1))((n_(3))/(n_(2))-1)t`
D. `(2 pin_(1))/(lamda_(1))(n_(3)-n_(2))t`

Answer

A

Explanation

Optical path difference between the waves `= (n_(3)-n_(2))t`
`:.` phase difference
`=2 pi ((n_(3)-n_(2))t)/(lamda_(("vacuum")))=2 pi ((n_(3)-n_(2))t)/(n_(1)lamda_(1))`.