3D40.35 • Chladni Plates (motorized version)

Faculty Instructions:

Turn down the amplitude to 0V while making adjustments to the system.
Choose desired plate (circular or square) and insert onto vibration generator.
Shake enough sand out of the sand container to evenly cover the plate. As shown above. (You may need to add more sand as the frequency increases).
Refer to the "Create Specific Patterns" section below for a glossary of frequencies and patterns available to demonstrate.
To set the frequency manually:
- Change the value of the highlighted digit by turning the knob labeled "Frequency" on the function generator.
- To change places within the frequency value, press and hold the frequency knob down as you turn to choose the desired place value. The selected digit will be displayed with a flashing underline.
- A sweeping mode is also available (refer to "Sweep Mode" instructions below).
Once the frequency is set, turn the amplitude up to at least half of the maximum voltage. A higher amplitude will produce more defined patterns.

Concepts Conveyed:

Chladni Plates convey standing wave patterns. When the plates are vibrating at a resonant frequency, nodes appear. The nodes are stationary while the rest of the plate is vibrating, causing the sand to accumulate at the nodes and form shapes and patterns. Boundary conditions such as pressing a finger to the plate alter the plate's vibration patterns hence altering the shape appeared.

Demo Staff Notes:

Connect the vibration generator to the function generator with the red and blue leads as shown above.
After plugging in the function generator, it should automatically turn on. If a consistent sound is made on initially turning on the function generator, turn down the volume by turning the amplitude to 0V.

Sweep Mode:

The sweep method allows you to set a start frequency, stop frequency, and the time for the range to run. As it runs the frequency increases within a set range and patterns of the sand change. It is recommended to use the INT. CONTINUOUS or the INT. SINGLE modes.
To begin sweep mode, plug the function generator in and allow it to turn on. The screen should display a frequency and the wave type.
Press the SWEEP button to activate the sweep mode. Set the start frequency to the desired value using the frequency knob. Press and rotate the knob to adjust a certain digit.

Press SWEEP again and use the frequency knob to change between "int. Continuous mode" and "int. Single mode".
- Continuous mode runs the frequency range over and over until prompted to stop.
- Single mode runs the frequency range ONCE then stops on its own. Single mode is suggested.

Finally, press sweep again, and the screen will display "ready". Once you are ready to begin, press the "Offset, Start/Stop" button to begin the sweep.
- If using continuous setting press Offset button again to stop.

Create Specific Patterns:

Constraints or Boundary conditions may be applied by pressing firmly on the plate with thumb and index finger.
- The * notation indicates a boundary condition approximately 1 in. from the edge of the plate.
- X indicates where on the plate the fingers were placed for that pattern.

Pictures show demonstration used at the University of Texas at Austin

square plate: 160 Hz circle plate: 120 Hz