When the angle of incidence is `60^(@)` on the surface of a glass slab, it is found that the reflected ray is completely polarised. The velocity of light in glass is

Options

A. `sqrt2xx10^(8)ms^(-1)`
B. `sqrt3xx10^(8)ms^(-1)`
C. `2xx10^(8)ms^(-1)`
D. `3xx10^(8)ms^(-1)`

Answer

B

Explanation

Refractive index of glass, `mu_(g)=tantheta_(p)`
where, `theta_(p)="polarising angle"rArrmu_(g)=tan60^(@)=sqrt3`
Now, `mu_(g)=c/v_(g)rArrc/v_(g)=sqrt3`
`rArr" "v_(g)=(3xx10^(8))/(sqrt3)=sqrt3xx10^(8)ms^(-1)`