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Question
Light enters from air to glass having refractive index 1.50. What is the speed of light in the glass? The speed of light in vacuum is 3 × 108 m s−1.
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Solution
Refractive index of a medium nm is given by,
`n_m="Speed of light in vacuum"/"Speed of light in the medium" = c/v`
Speed of light in vacuum, c = 3 × 108 m s−1
Refractive index of glass, ng = 1.50
Speed of light in the glass,
`v = c/n_g`
`= (3 xx 10^8)/1.50`
`= 2 xx 10^8ms^(-1)`
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