Question

The index of refraction for crown flint glass is 1.575. What is the speed of light in crown flint glass

Answer 1

Given :

Refractive index (μ) of crown flint glass = 1.575

To Find :

The speed of light in crown flint glass

Solution :

We know,

                           Refractive index (μ)     = $\frac{Speed of Light in Vaccum}{Speed in Medium}$

or,                              1.575                      = $\frac{3 * 10^{8} }{Speed of Light in Glass}$

or,   Speed of Light in crown flint glass = $\frac{3 * 10^{8} }{1.575}$

                                                                = 1.9 × $10^{8}$ m/sec

∴ The speed of light in crown flint glass having refractive index 1.575 is 1.9 × $10^{8}$ m/sec.

Note - The value of the refractive index depends on -

1. Nature of the two concerned media
2. Colour of the incident light.

Answer 2

Given:

Refractive index of crown flint glass = 1.575

Speed of light in vacuum = $3*10^{8}$ m/s

To Find: Speed of light in crown flint glass

Calculation:

• Refraction of light is the phenomena of light to bend when travelling from one medium to another medium.
• Refractive index of any medium is defined as the ratio of speed of light in vacuum to the speed of light in that particular medium.
• The degree of refraction or the amount of bending that the ray of light will go through will depend on the refractive index of medium.

Let refractive index of the glass be n, let speed of light in that medium be v and speed of light in vacuum be c.

$n=\frac{c}{v} \\1.575=\frac{3*10^{8}}{v} \\v=1.90*10^{8}$ m/s

Answer:

Speed of light in crown flint glass is 1.90*$10^{8}$ m/s.