Refractive index of glass with respect to medium is `(4)/(3)`. If `v_(m) - v_(g) = 6.25 xx 10^(7)` m/s., then velocity of light in medium is

Options

A. `2.5 xx 10^(8) m//sec`
B. `1.5 xx 10^(7) m//sec`
C. `2.25 xx 10^(8) m//sec`
D. `4.5 xx 10^(7) m//sec`

Answer

A

Explanation

`._(m)mu_(g) = (4)/(3), v_(m) - v_(g) = 6.25 xx 10^(7), v_(m) = ?`
`._(m)mu_(g) = (v_(m))/(v_(g)) = (4)/(3)`
`:. v_(g) = (3v_(m))/(4)`
`v_(m) - v_(g) = 6.25 xx 10^(7)`
`v_(m) - (3v_(m))/(4) = 6.25 xx 10^(7)`
`(v_(m))/(4) = 6.25 xx 10^(7)`
`v_(m) = 2.5 xx 10^(8) m//s`