Step-by-step explanation:
The speed of light when it travels through glass, diamond, etc, the light travels at different speed from the speed of light. Speed of the light in material is related to the index of refraction.
Hence, light have different speeds in different medium and also, will have different wavelength in different mediums.
The change in speed which occurs when the light passes from one medium to the another is responsible for bending of the light which is called as refraction.
Further, if the light travels from a low denser medium to high denser medium, it refracts towards the normal and if the light travels from high denser medium to low denser medium, it refracts away from the normal. The refraction of light happens at the point of incidence.