Oscillation and Waves
Chaotic pendulums
A double, or chaotic, pendulum undergoes simple harmonic motion when the initial displacement from equilibrium is small. However, increasing this displacement gives way to chaotic motion, demonstrating the absence of predictability in a non-linear system.
Rubens’ tube
The Rubens’ tube is a long, closed tube with propane pumped in and holes drilled along the top for the propane to escape. Igniting the propane along the top gives a “wall” of fire where propane and oxygen are present. Playing a pure tone in the tube will create sinusoidal peaks and valleys in the […]
Pendulum Waves
The period of a pendulum, at small amplitudes, depends only on it’s length. The pendulum’s lengths in this demonstration were carefully designed to oscillate 45, 46,…,59, and 60 times per minute. When put into oscillation together, these slight differences in frequencies creates synchronous waves in the pendula before coming back to its initial position exactly […]
Chladni plate
A metal plate with fine sand sprinkled on top is forced into resonance with a stringed bow. The resonating plate has nodal areas in which the plate does not vibrate, and the sand is undisturbed, and the sand collects in these areas. This gives a great visual representation of the different resonant modes of this […]
Diddley bow
A hand-made electric guitar demonstrates how magnetic pickups convert the vibrating guitar string into currents that can be amplified and modulated. The guitar has a variable amplifier and signal modulator built in and adjustable with dials. This then gets fed into a commercial amplifier as a normal electric guitar would.
Coupled Oscillator
This involves two masses on two separate strings hanging from a thin rod. As each mass oscillates as a simple pendulum, they become coupled by vibrations of the rod, demonstrating physics concepts such as resonance and synchronization.
Sonometer
A guitar string is suspended over a hollow wooden box, and pulled taut by free-hanging weights. By increasing the weight on the end of the string, the tension is increased, and the pitch of the sound that the sonometer produces increases. By moving a bridge positioned on top of the string, the string’s effective length […]
Microwave Grape Plasma
We create plasma with grapes by first cutting them in half, with the skin joining them still intact. The skin joining the two halves heat up, vaporize and burst into flame creating a plasma.
Sound in a vacuum
Sound waves are the compression and rarefaction of a medium, usually air. If we remove the medium, by vacuum, the sound has no way to propagate and we are not able to hear anything.
Foucault Pendulum
Due to the pendulums inertia, once started, it will oscillate in the same plane forever. However, since the pendulum is on Earth which rotates about its own axis, from our rotating point of view the pendulum’s plane of oscillation seems to be what’s rotating. The period of rotation depends on your latitude too: at the […]