Dancing Sand Grains on a Square Chladni Plate

At a frequency of 330 Hz a nodal pattern develops.

Discussion

With the wave driver at a frequency a little below 330 Hz, sand is scattered on the plate and an indistinct nodal pattern gradually forms, as sand grains dance away from antinodal areas and collect in nodal areas. When the driving frequency is increased to 330 Hz, a resonant frequency, a clearly defined pattern quickly takes shape.