When a stone is thrown in the water say pond, tank etc. you have noticed that many small waves of water are formed which moves away from the point where stone hits the water. These are known as ripples.

Water in liquid state is not fixed sheet so it can easily changes the shape. When a stone or an object is thrown into the water some energy transformation takes place moreover a particular volume of water gets displaced which equal to the volume of the stone or the object thrown. As we said earlier that water is in liquid state so it does not get compressed but depressed and forced up after reaching its original level it goes on somewhat further and starts moving to the other sides which leads to the formation of ripples. The size of ripples depends on the energy of the moving object. When the water moves backward to fill the displaced water it is known as secondary ripples. When the outward moving ripple strikes with inward moving ripple they eject a drop of water which when again hits the water surface forms another chain of water ripples which are small than the previous one.

These deformations on the surface of water can be explained by the mathematical equations which are very complex ones. These equations give the solution for small deformations and well behaved waves.