Final answer:
Refraction is the bending of light or sound waves when they pass from one medium to another due to changes in velocity, which is particularly evident in transitions from air to water and vice versa.
Step-by-step explanation:
The phenomenon described in the question is known as refraction. Refraction occurs when light or sound waves pass obliquely from one medium to another, resulting in a change in the path of propagation due to the different velocities of wave travel in these media. This altering of the path is typically referred to as the bending of waves. For example, when light travels from air into water, it slows down due to water's higher density compared to air, which causes the light to bend at the boundary between the two environments.
Refraction is not only limited to light; it can also apply to sound waves. The principles of refraction are responsible for various optical phenomena, such as the focusing effects of lenses, as well as technological applications like transmitting voice through optical fibers.
It is important to note that refraction differs from diffraction, which is the bending of waves around the edges of an opening or an obstacle.