The refractive index of glass is 1.5. What is the speed of light in glass? (Speed of light in vacuum is 3.0 × 108 m s−1) - Physics

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The refractive index of glass is 1.5. What is the speed of light in glass? (Speed of light in vacuum is 3.0 × 108 m s−1)

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Solution 1

Refractive index of glass, μ = 1.5

Speed of light, c = 3 × 108 m/s

Speed of light in glass is given by the relation

`"v" = "c"/μ`

= `(3 xx 10^8)/1.5`

= 2 × 108 m/s

Hence, the speed of light in glass is 2 × 108 m/s.

Solution 2

Given:

Refractive index of glass = 1.5

Speed of light in air = 3.0 × 108 m/s

Speed of light in glass = ?

Applying the formula for refractive index, we get:

Refractive index of a medium = (Speed of light in air)/(Speed of light in medium)

For glass:

Refractive index of glass = (Speed of light in air)/(Speed of light in glass)

(Speed of light in glass) = (Speed of light in air)/(Refractive index of glass)

= (3.0 × 108)/1.5

= 2.0 × 108 m/s

Concept: Reflection and Refraction of Plane Wave at Plane Surface Using Huygens' Principle - Refraction of a Plane Wave
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Chapter 10: Wave Optics - Exercise [Page 383]

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NCERT Physics Class 12
Chapter 10 Wave Optics
Exercise | Q 10.3 (a) | Page 383
NCERT Physics Class 12
Chapter 10 Wave Optics
Exercise | Q 3.1 | Page 383

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