NCERT Solution for Class 10 Science Chapter 10
Light – Reflection and Refraction
NCERT Books for Session 2022-2023
CBSE Board and UP Board
Intext Questions
Page No-176
Questions No-2
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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The speed of light in a medium is related to its refractive index (n) by the equation:
v = c/n
where:
» v is the speed of light in the medium,
» c is the speed of light in a vacuum,
» n is the refractive index of the medium.
In this case, the refractive index (n) of glass is given as 1.50, and the speed of light in a vacuum (c) is 3 ×10⁸ m/s
Substituting these values into the equation, we get:
v = 3 ×10⁸ m/s/1.50
v = 2 ×10⁸ m/s
So, the speed of light in the glass is 2×10⁸ m/s.
Speed of light in vacuum, c = 3 × 10⁸ m s−¹
Refractive index of glass, n = 1.50
Speed of light in the glass, v = c/n = 3×10⁸ m s−¹
Refractive index of glass, n = 1.50
Speed of light in the glass, v= c/n = 3×10⁸/1.50 = 2×10⁸ ms−¹
Refractive index of a medium, nm = Speed of light in vacuum/Speed of light in the medium
Speed of light in vacuum, c = 3 × 108 ms-1
Refractive index of glass, ng = 1.50
Speed of light in the glass, v = Speed of light in vacuum/ Refractive index of glass
= c/ng
=3 × 108/1.50 = 2x 108 ms-1.
Refractive index of a medium nₘ is given by,
nₘ = 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, n = 1.50
Speed of light in the glass, v = c/n = 3×10⁸ m s−¹
Refractive index of glass, n = 1.50
Speed of light in the glass, v= c/n = 3×10⁸/1.50 = 2×10⁸ ms−¹
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