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 vacuume is 3×10^8​

Answer 1

Given :-

Refractive index of the glass = 1.50

The speed of light in vacuum = 3 × 10⁻⁸ ms⁻¹

To Find :-

The speed of light in the glass.

Solution :-

We know that,

• nm = Refractive index of a medium
• c = Speed of light in vacuum
• ng = Refractive index of glass
• v = Speed of light in the glass

According to the question,

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

Given that,

c = 3 × 10⁻⁸ ms⁻¹

ng = 1.50

Substituting their values,

= 3 × 10⁸/1.50

= 300000000/1.50

= 200000000 = 2 × 10⁸ ms⁻¹

Therefore, the speed of light in the glass is 2 × 10⁸ ms⁻¹.

Answer 2

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 m/s

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.