Can absolute refractive index of any material be less than one? Why?

Define absolute refractive index.

Can relative refractive index of a medium w.r.t another be less than unity?

A thin douel convex lens has surfaces of radii of curature 30 cm each.Find the refractive index of the material of lens,if the focal length is 25 cm.

A thin prism of 20^@ angle gives a deviation of 1^@ . What is the value of refractive index of the material of the prism?

A thin prism of 2^@ angle gives a deviation of 1^@ . What is the value of refractive index of the material of the prism?

A thin prism of 5^@ angle gives a deviation of 3.2^@ .What is the value of refractive index of teh material of the prism?

A lens behaves as a converging lens in air and diverging lens in water.The refractive index of the material of the lens is

For which colour,the refractive index of the material of prism is maximum and minimum?

The refractive index of a material is sqrt3 . What is the angle of refraction if the unpolarised light is incident on it at the polarising angle of the medium.

A ray is incident at an angle of incidence i on one surface of a prism of small angle A and emerges normally from the opposite surface. If the refractive index of the material of the prism is mu , the angle of incidence i is nearly equal to