Answer:
If the light enters one medium to another medium then the speed of light gets change.
Step-by-step explanation:
When the light enters from rare medium to denser medium then the light gets bend towards normal.
When the light enters from denser medium to rarer medium then the light gets bend away from normal.
If the light enters one medium to another medium then the speed of light gets change and the direction of light also gets change. Only the frequency of the light remains during this phenomenon. The wavelength of the light gets decreased.