Physicists make Tibetan bowls sing, fizz, and spitS

Tibetan singing bowls have been used to produce beautiful and eery sounds. Now physicists are using them when they're full of water to create a reverse-rainstorm.

Tibetan singing bowls are generally made of bronze. They're all different sizes, and come with small, round sticks called pujas. When the bowls are struck, or when the sticks move around the rim of the bowls, the bowls give off a loud, monotonous tone. The tones vary depending on the size, shape, and composition of the bowl, as well as the liquid inside it. The physics of the bowls are the same as a tuning fork, or a wineglass that is stroked around its rim. The friction of an object moving against it causes the overall object vibrates at a certain frequency. This vibration gives off the tone that we hear when a wine glass is played, or a tuning fork is struck.

Tibetan singing bowls can get a little more dramatic during their songs, though. The bowls' malleability and mass cause the water inside it to move dramatically. The resonance of the bowl causes the waves on the water inside that build up with time and continued vibration. Eventually, the waves get high enough to break against each other, releasing droplets into the air above the bowl.

The bowl fizzes and spits water into the air. These waves can be studied to see how water droplets broke away from the main body of water when the surface of the water was sufficiently excited. Researchers at MIT looked into the phenomenon in detail. To keep the vibration even and remove any variables, the researchers did not use the wooden pujas to vibrate the bowls. Instead they set up speakers near the bowls and played tones that caused the bowls to vibrate. They used high speed cameras to examine the resulting droplets.

The way that droplets break away from waves could have implications for fuel injection systems and perfume atomizers, but currently, it's just physicists playing around. If you had a high speed camera, a Tibetan singing bowl, and a stereo system, wouldn't you do the same?

Via Iop Science