Question

(a) The refractive index of glass is `1.5`. What is the speed of light in glass ? (Speed of light in vaccum is `3 xx 10^(8) ms^(-1)`).
(b) Is the speed of light in glass independent of colour of light ? If not, which of the two colours, red and violet travels slower in a glass prism ?

Answer 1

Refractive index of glass `,mu =1.5 `
Speed of light ` C=3xx10^(8) m/s`
Speed of light in glass in given by the relation ,
`V=(C)/(mu)`
`=(3xx10^(8))/(1.5 ) = 2xx10^(8) m//s`
Hence , the speed oflight in glass is `2xx10^(8)` m/s .
(b) The speed of light in glass is `2xx10^(8)`m/s
the refractive index of a vioet component of while light is greater than the refractive index of a red compount Hence , the speed of vioet is less than the speed of red light in glass in glass .Hence , violt travels slower than red light in a glass prism.