Arvind MR asks:

“if a drop of water is dropped in a bucket we can notice that a wave is created and it moves away as a ring……but i see that it rebounds back and come to a point again but not the starting position ……so the number no times this happens depend upon the height we drop the water droplet…..my question is why the wave rebounds after touching the ends of the bucket?”

Answer:

See the animations here and try explaining yourselves

Watch an interactive animation on reflection of waves here.

http://wildcat.phys.northwestern.edu/vpl/waves/wavereflection.html