bending of a wave as it passes from one medium to another.AreflectionBrefraction

The phenomenon described in your question refers to "B" refraction. Refraction occurs when a wave, such as light or sound, travels from one medium to another and experiences a change in speed, which results in the bending of the wave. This bending is governed by Snell's Law, which relates the angles of incidence and refraction to the indices of refraction of the two media.

In contrast, "A" reflection refers to the bouncing back of a wave when it hits a surface that it cannot pass through. While both phenomena involve changes in direction, refraction specifically pertains to the change caused by transitioning between different media, while reflection pertains to the wave returning in the opposite direction.

In practical terms, you can see refraction in action when a straw appears bent when placed in a glass of water due to the light bending as it moves from air (one medium) into water (another medium).