Question

Light enters from the air to glass having the refractive index 1.50. what is the speed of light in the glass ? the speed of light in vacuum is 3×20^8


For class 10


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Answer 1

Question:

Light enters from the air to glass having the refractive index 1.50. what is the speed of light in the glass ? the speed of light in vacuum is 3×20^8

Answer:

Speed of light in vacuum (c) = 3 × 108 ms-1

Refractive index of glass (ng) = 1.50

Refractive index of a medium = Speed of light in vacuum/Speed of light in the medium

Refractive index of glass = Speed of light in vacuum/Speed of light in the glass

Speed of light in the glass (v) = Speed of light in vacuum/ Refractive index of glass

v = c/ng

v = (3 × 108)/1.50

v = 2 × 108 ms-1

Answer 2

Explanation:

Given,

Refractive index ( n ) = 1.50

Speed of light in vacuum ( c ) = 3 x 10^8 m/s

To find :

Speed of light in glass ( v ) = ?

Formula : -

n = c / v

v = c / n

= ( 3 x 10^8 ) / 1.5

Multiply 10 to both numerator and denominator,

= ( 30 x 10^8 ) / 15

= ( 30 / 15 ) x 10^8

n = 2 x 10^8 m/s

Therefore,

the speed of light in the glass is 2 x 10^8 m/s.