If the critical angle for total internal reflection from a medium to vacuum is `30^(@)`, the velocity of light in the medium is

Options

A. ` 2 xx 10^(8) m//s `
B. `1.5 xx 10^(8) m//s `
C. `1.8 xx 10^(8) m//s `
D. `2.25 xx 10^(8) m//s `

Answer

B

Explanation

`n=(V_a)/(V_m)=(1)/(sin C)`
`:. V_m=V_a sin C=V_a sin 30^(@)`
` = 3 xx 10^(8)xx (1)/2 =1.5 xx 10^(8) m//s `