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Question
Numerical problem.
Light enters from air into a glass plate having refractive index 1.5. What is the speed of light in glass? (Ans: 2 × 108 ms–1)
Solution
Given: Refractive index (µ) = 1.5
Speed of light in vacuum (c) = 2 × 108ms– 1
Speed of light in glass (υ) = ?
Solution:
µ= `"Speed of light in vacuum (c)"/"Speed of light in glass (υ)"`
1.5 = `(2×10^8"ms"^(-1))/"υ" ⇒ "υ" = (2×10^8"ms"^(-1))/1.5= 1.3 × 10^8 "ms"^(-1)`
∴ Speed of light in glass = `1.3 × 10^8 "ms"^(-1)`
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