Image on black and white television is deflected by a magnet, not unlike the Maltese Cross.
What it shows: The television is basically a sophisticated cathode ray tube. The electron beam in the TV is influenced by magnetic fields in the same way as in Crookes tubes.
How it works: The image on a black & white TV is formed by a single electron gun scanning the screen. Holding a strong magnet to the side or in front of the screen deflects the beam from its regular sweep pattern, distorting the image.
A lecturer's faith in the principle that an electric field cannot exist inside a charged conductor is put to the test using a Faraday cage that is large enough to sit in.
How it works:
The lecturer (or some volunteer) climbs the three steps and sits upon a plain wooden chair. Their assistant pulls the mesh door closed and fastens it. A Van de Graaff, whose dome is in contact with the cage, begins to charge itself and the cage up to a high voltage. The person inside is oblivious to the large amount of charge now...
Two speakers, one at each end of rotating platform; beating due to frequency shift of speakers travelling in opposite directions.
What it shows:
Doppler shifting of sound to higher frequencies occurs when a source is moving towards the observer, and shifted to lower frequencies when the source is moving away. Here two sources emitting the same frequency when stationary rotate on a turntable. With one source moving towards you and one away, the Doppler shifted waves interfere to create beats.
Standing sound waves in a glass pipe are made evident by the fountains of kerosene inside the pipe.
What it shows:
The air inside a very large glass pipe (partially filled with a fluid) is acoustically excited into a standing wave. Once resonating, the locations of the velocity antinodes inside the pipe are dramatically made evident by the vigorous agitation of the fluid, resulting in fabulous foaming frothing fountains of fluid. The velocity of sound can also be determined by noting the resonance frequency and measuring the distance between antinodes....