Glow Discharge Tube

Pressure changes are not the only way to observe glowing particles. Electrons can move from one energy level to another in an atom when enough energy is added. As they jump to the next level and then return to their original state they give off light energy.

To observe the “jumping and falling” of electrons you will need a darkened room, UV light and chlorophyll. UV light is not visible to the human eye because it has a higher frequency wavelength than visible white light. However, energy from UV is easily absorbed by certain compounds such as plant chlorophyll.


Take several handfuls of green pine or cedar needles and carefully tear or chop them into small pieces. Place them in a glass container and pour isopropyl alcohol over them to cover the pieces completely. Mix carefully to make sure all the pieces are exposed to the alcohol. Put a secure lid or cover over the container to prevent evaporation of alcohol. Allow the mixture to stand for several hours (or overnight) to cause the chlorophyll to be extracted from the needles.

Pour the green liquid into a clear glass container. (Use a filter to prevent any pieces of needles from getting into the new container.) Darken the room and shine a UV light through the green liquid. Observe the new color of the liquid. Compare the color of the liquid when ordinary white light is used to shine through the liquid. Why does the color change?