Chladni Plates

When a flat metal plate is vibrated, sand sprinkled on its surface collects at the nodal lines where no motion occurs. This creates symmetrical patterns, known as Chladni figures, which reveal the modes of vibration of the plate.

1. Mount a flat metal plate (circular, square, or other shape) on a central stalk fixed to a sturdy base.
2. Clamp the base securely to a stable surface.
3. Sprinkle fine sand evenly across the plate.
4. Hold the edge of the plate at one point with a finger or fingernail to create a node.
5. Use a violin or cello bow (well-rosined) to draw across another point on the edge.
6. Adjust bowing position and pressure until the plate vibrates loudly.
7. Observe how the sand shifts away from areas of strong vibration (antinodes) and collects along nodal lines, forming distinct patterns.

Chladni Plates - Harvard Natural Sciences Lecture Demonstrations:

Chladni Plate | STEM Demonstration - MIMphx:

📄 Chladni Plates - Harvard Natural Sciences Lecture Demonstrations: https://sciencedemonstrations.fas.harvard.edu/presentations/chladni-plates

• Try plates of different shapes (circle, square, stadium-shaped) to compare nodal patterns.
• Change the bowing point to excite different modes of vibration.
• Use different granular materials (such as salt or sugar) to compare visibility of the patterns.
• Record the demonstration with a camera to capture the formation of patterns in slow motion.

• Clamp the base firmly to prevent slipping during bowing.
• Handle the bow carefully to avoid injury from slipping strings or excessive rosin dust.
• Keep sand away from eyes and avoid inhaling fine particles.
• Protect nearby electronic equipment from stray sand.

• Why does sand collect at the nodal lines? (These are points of no vibration, so the sand naturally settles there.)
• How does changing the bowing position affect the pattern? (It excites different modes of vibration with distinct nodal arrangements.)
• Why are the patterns symmetrical? (The plate vibrates according to its geometry, producing standing wave patterns consistent with its shape.)
• What might happen if you used a plate of irregular shape? (The patterns would still form but would be less regular and symmetrical.)