Move detector around x-ray tube to show that x-rays come out preferentially in the forward direction. Ask for absorbers if you wish. Looking at the close-up photograph at the right above, electrons originate from the electrode at the upper right and strike the anode from its right side, producing x-rays that move preferentially to the right from the cathode.

Note: This demonstration is rather touchy to set up to actually obtain x-rays. It is available largely so that the geometry of such a tube can be seen by the students.

Optionally, a light source can be provided with different coulour filters. The light source provides a photon of energy. With a red filter the ball jumps one step; with the blue filter the electron jumps two or three steps up the ladder. Radiation with the wrong light, say green light, leaves the ball in its ground state (on the floor), because that energy would leave the ball between energy levels. Invite students to make predictions about the results of different colours of light/different amounts of absorbed energy.

A set of liquid vials containing fluorescent materials is illuminated by an ultraviolet light source. The radiation is absorbed by the chemicals and emitted at a visible frequency, causing them to glow. Identification of the chemical is printed above each vial. The bottle at the right contains quinine water. It's almost enough to make you give up drinking quinine water.

The second photograph was taken with normal fluorescent lighting.

The spectrum of a carbon arc lamp, projected onto a screen, contains both visible and ultraviolet radiation. A wavelength shifter bar is a plastic material containing a fluorescent chemical, fluorescien. Insert the wave length shifter bar into the spectrum with light coming out the curved end aimed at the class for easier observation. For wavelengths greater than green, the spectral color is observed (red, orange, yellow). For shorter wavelengths, the chemical in the bar absorbs the incident light but re-emits that energy as green light, the characteristic color of the chemical in the plastic tube.

Use the wave length shifter bar to demonstrate the existence of ultraviolet radiation in the spectrum of the carbon arc lamp.

Wintergreen mints are smashed IN A DARK ROOM between two glass plates, as pictured above, or by biting into one. When the mint breaks, a small flash of bluish light is produced.

When a sugar crystal in the mint is broken, it is often separated into two sections with different charges, creating a potential difference. If enough crystals are fractured simultaneously, the potential becomes large enough to cause electrons in the structure to be repulsed from one region and attracted to another. In transit, these electrons strike other electrons in nitrogen molecules in the air, raising the atomic electrons to excited states. When the electrons decay they emit ultraviolet radiation that strikes molecules of methyl salicylate flavoring in the wintergreen mint. These molecules of methyl salicylate flavoring absorb the UV radiation and re-emit it as the blue light observed when the mint fractures.

Instructor must provide mints.