Ans. REFLECTION OF WAVES
When waves moving in one medium fall on the surface of another medium, they bounce back into the first medium such that the angle of incidence is equal to the angle of reflection. This phenomenon is called reflection of wave.
Now, we explain the reflection of waves with the help of ripple tank.
Place a bar in the ripple tank, the reflected wave can be seen to obey the law of reflection. The ripples will reflect from the bar. If the bar is placed at an angle to the wave front i.e. the angle of the incident wave along the normal will be equal to the angle of reflected wave