Question

Q2) Someone claims he has chemically produced a material with the index of refraction of 0.95.
Comment on this claim

Answer 1

Refractive index value less than one is not possible.

Because, as we have read in the definition of refractive index of a material in the text book -

refractive index (n) = Speed of light in vaccum / speed of light in that material

Now, speed of light in the vaccum = 3 x 10^8 m/s

so, when the material has refractive index of 0.95, it means -

speed of light in the material = (3 x 10^8) / 0.95 = 3.16 x 10^8 m/s

and this is not possible because at any case, speed of light cannot be greater than 3 x 10^8 m/s.

So, the claim is wrong.