Solution

A ripple tank is used in labs to produce water waves. It consists of a shallow water tank with a transparent base and a white screen placed beneath it at some distance. It is illuminated by a light source above the tank. Waves are generated by a dipper run by a motor. When light falls on water, the images of ripples (means small waves) are seen on the screen beneath it.

Since the light travels more distance in water while passing through the crest than the trough, therefore, more light is absorbed in the crest. It produces dark image on the screen. The trough where little light is absorbed seems brighter.

Different wave characteristics like reflection, refraction are studied in the laboratories through the ripple tank.