Waves reflecting from two surfaces can interfere constructively and destructively. In this case it is light waves that are being reflected from the front and rear surfaces of thin soap or oil films. The interference produces a pattern of beautiful colors in white light, or dark and light bands in monochromatic light.
How it works:
Our two most visually dramatic illustrations of thin film interference use either a soap film suspended in air from a 19 cm diameter circular frame, or a very thin layer of oil floating on top of water....
Unlike the continuous spectrum emitted by blackbody radiators, the light given off by atoms in a gaseous discharge is characterized by its discreet nature. Using street lamps for the light sources, bright atomic spectra of mercury or sodium are projected onto a screen.
The demonstration shows density fluctuations in liquids. These fluctuations are particularly spectacular near critical points. A binary fluid mixture of methanol (29% by weight) and cyclohexane (71%) becomes opalescent when heated up to its critical temperature (about 45˚C) ... the fluids become miscible above this temperature.
How it works:
The two fluids are sealed in a special vial, able to withstand elevated pressure. The fluids are immiscible at room temperature. When brought up to 45˚C, they become miscible...
As demonstrated by two people throwing a volleyball to each other while sitting on rotating platform.
What it shows:
The Coriolis force is a pseudo force existing in a frame that rotates with constant angular velocity to a reference frame. It acts on a body moving in the rotating frame to deflect its motion sideways. Here the audience sits in the reference frame, while two volunteers on a rotating platform experience the coriolis force by trying to basket a volleyball.
What it shows: Using the classical description of the motion of a spin in an external magnetic field, the demonstration helps visualize NMR in the time domain. The nuclear magnet and its classical vector model are represented by a spinning ball with magnets attached. A rotating mass is characterized by its angular momentum L, which is the analog of the magnetic moment mu, which characterizes a rotating charge distribution. The spinning ball mimics protons in that it has both angular momentum as well as an "intrinsic" magnetic moment. The torque...
A straightforward demonstration of Newton's 3rd law, that forces are interactions and thus come in pairs.
How it works:
Two people, each sitting (cross-legged) on their own board, position themselves in the center of the track facing each other. Upon pushing against each other with their hands, they glide apart down the length of the track. Repeat this with one person turned around — the other person pushes on his/her back instead of pushing against each other with their hands. The ensuing motion down the track is exactly the same as before.