In explaining the electron orbits in the Bohr atom, de Broglie's principle of particle wave duality allows you to treat the electrons as waves of wavelength nλ = 2πr where r is the radius of the orbit. Then the only orbits allowed are those which are integer...
Blue balloon with hydrogen, green balloon with helium, red balloon in back with hydrogen and oxygen mixture, and, on a cart, a red water balloon on large watch glass. Candle on a stick with matches, and a needle in the end to prick the water balloon.
Safety glasses and hearing protection is required for the demonstrator and anyone else who can't cover their ears for the red balloon.
Apple electronically released from platform; fall time given by special circuit and digital display.
What it shows:
This is a free-fall-from-rest experiment in which an apple (or any other object of comparable size) is dropped from the lecture hall ceiling into a catching bucket on the floor. By measuring the (1) distance and (2) duration of the fall, an accurate (± 0.022%) determination of the acceleration due to gravity can be made:
A liter of warm water in large pyrex vessel, covered with fine mesh stainless steel screen, is on a stool close by in-floor vent hood. Add a few drops from the phenolphthalein indicator bottle.
Using the long forceps, pick out a pea size lump of sodium metal from the mineral oil in the small beaker. Wipe off the lump on the dry paper towels. With the vent fan running, lift the edge of the screen and drop in the sodium metal. Replace the screen and get back.
The sodium will from a hissing ball of molten metal, which bounces...
A Van de Graaff generator will apply a charge to its dome and anything else in contact with the dome. Should that object be a person, they obtain a net surplus of charge (be it positive or negative). It is especially noticeable with hair, as each individual strand is repelled from every other and from the scalp.
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....