Question

Q2. The speed of light in a transparent medium is 0.6 times that of its speed in
vacuum. Find the refractive index of the medium.​

Answer 1

Given that, speed of light in a transparent medium is 0.6 times that of its speed in

a vacuum.

We have to find the refractive index of the medium.

Let us assume that speed of light in a vacuum is 'M'.

Coming back to question again!

Speed of light in a transparent medium is 0.6 times that of its speed in

a vacuum.

⇒ Speed of light in a transparent medium = 0.6 × Speed if the light in vacuum

{ Speed of light in vacuum = M

As per assumption }

⇒ Speed of light in a transparent medium = 0.6 × M

Now,

Refractive index = (Speed of light in vacuum)/(Speed of light in medium or transparent medium)

Refractive index = M/(0.6 × M)

Refractive index = 1/0.6 = 1.67

Answer 2

Given :-

The speed of light in a transparent medium is 0.6 times that of its speed in  vacuum.

To find :-

The refractive index of the medium.​

Solution :-

Let the speed of light in vacuum be x.

A/q, speed of light in the transparent medium = 0.6x.

We know, refractive index of the medium =

Speed of light in vacuum (or air)/Speed of light in medium-2 i.e. transparent medium

So, refractive index = x/0.6x

R.I = 1/0.6

⇒R.I = 5/3

∴ So, the refractive index of the medium is 5/3(or 1.67).