Refractive index of glass w.r.t water is `9//8`. What is the speed of light in water ? Given speed pf light in glass is `2 xx 10^(8) m//s`.

Options

A. `1.6 xx 10^(8) m//s`
B. `1.33 xx 10^(8) m//s`
C. `3 xx 10^(8) m//s`
D. `2.25 xx 10^(8) m//s`

Answer

D

Explanation

`v_(g) = 2 xx 10^(8)m/s, ._(w)mu_(g) = (9)/(8), v_(w) = ?`
`._(w)mu_(g) = (v_(w))/(v_(g))`
`v_(w) = v_(g)._(w)mu_(g)`
`= 2 xx 10^(8) xx (9)/(8)`
`= 2.25 xx 10^(8) m//s`