PROJECTS: CHLADNI PLATE
makezine.com/16/chladni
WAVE
WATCH
Vibrating surfaces move and flex in some places while remaining relatively still in others.
Powder sprinkled on a flat, vibrating surface will flee the moving areas and settle in the
still areas. When the vibrations are steady and at the right frequency, this creates a pattern
of standing waves that shows how the material is vibrating.
HOW IT WORKS
A speaker’s magnet
assembly has a ring
magnet, a pole piece,
and front and rear plates
that hold them together.
CHLADNI PLATE
AND SHAKER
ASSEMBLY
The ring magnet creates
the magnetic field that
the voice coil pushes
against.
The pole piece helps
contain and shape the
magnetic field.
The voice coil consists
of a thin-walled former
and the coil itself, the
wire wound around it.
Electricity moving back
and forth through the
wire turns the coil into
an electromagnet of
varying polarity and
strength that moves
within the ring magnet’s
field.
The voice coil connects
to the plate.
Plate
Screw mount
Plastic cup
Aluminum tape
Voice coil
Ring magnet
The signal generator
feeds a pure oscillating
signal into the voice coil,
and the resulting vibrations travel outward and
bounce back from the
plate edges. We adjust
the signal’s frequency,
and when the plate can
physically resonate at
a particular frequency,
it settles into a stable
pattern: a standing wave.
9
7
7
56
65
2
2
1
4
4
1
The nodes are the still
areas where the powder
collects.
3
8
The antinodes are the
clean areas where the
plate moves the most.
SPEAKER
DRIVER
1 Ring magnet
2 Front plate
3 Rear plate
4 Pole piece
5 Voice coil
6 Former
3
7 Spider
8 Vent
9 Signal wires
PATTERNS
The pattern depends on the shape of the
surface and the frequency of the vibrations;
higher frequencies produce denser patterns.
Since acoustic musical instruments produce
sound by vibrating, these visualizations
can be used to understand and improve an
instrument’s design.
Illustration by Damien Scogin
124 Make: Volume 16
