Question

The speed of light in certain transparent is two fifth of its speed in air. The index of refraction is​

Answer 1

We know that μ=  

v

c

​  

     

                                      where v=speed of light in medium

                                                  c=speed of light in vacuum

                                         and   μ=refractive index of medium

Now,  

2

3

​  

=  

v

3×10  

8

 

​  

 

⟹v=2×10  

8

m/s..