When light enters from one medium to anathor no bending occurs means what?
Answers
The bending of light as it passes fromone medium to another is called refraction. The angle and wavelength at which the light enters a substance and the density of that substance determine how much the light is refracted.
How can no refraction occur when light goes from one medium to another of the same refractive index?
If the refractive index is the same, there is no reason for the light to bend. Light will not spontaneously turn direction for no reason.
The reason that light bends, or refracts, when it goes from one medium to another is because the light changes speed. Refractive index n is the factor by which the light slows down relative to the speed in vacuum c0. So the actual speed is v=c0/n. Now when the speed of a wave changes, so does the wavelength λ. In a vacuum, the wavelength is called the free space wavelength λ0 because the frequency is constant. The two are related through refractive index according to λ=λ0/n. Here is a link to an animation showing the wavelength and speed changing as a wave goes from one medium into another.