What is refractive Index ?

If the refractive index from air to glass is 1.5 ,and the refractive index of water is 1.33. What is the refractive index from glass into water?

The refractive indices of a diamond and water are 2.4 and 4//3 , respectively. What is the refractive index of diamond relative to water?

A ray of light falls on a material body at an incident angle of 30^(@) and refracted at angle 60^(@) . What is the refractive index of the material?

A ray of light falls on a material body at an incident angle 60^(@) and refracted at angle 30^(@) . What is the refractive index of the material?