Eli5: Can someone explain me the Chladni figures?


How and why do they form?

In: 2

Tie one end of a rope to something sturdy. Tension the rope and start swinging it up and down. It will alternate between an U and an ∩ shape. The both ends, which don’t move nearly as much, are called nodes. Now swing it twice as fast (double the frequency), and it will form an ~ shape with another node in the middle. You can conceivably keep going, adding more nodes.

Metal plates also swing like that when they vibrate, but in two dimensions. The nodes don’t form points, but rather patterns. When tiny grains are put on top of the plate, they’re thrown away from the strongly vibrating areas (called antinodes) and collect at the nodes. Different frequencies form different node patterns, and if a change in frequency turns a node into an antinode, the grains lying there hop away to the newly formed ones.