Neon - What makes it glow?
The first detection of neon glowing actually occurred in the late 1700's! It was dicovered by mistake of course. Aren't all great discoveries found that way? The French were the first to actually make a neon tube glow and illuminate. The first neon sign arrived in the United states in the 1920's.
Neon is an inert gas. Oderless, tasteless and colorless. It's even non-toxic! By itself, it does nothing much. However, if neon is sealed in a clear glass tube in a pure state, a current of electricity flowing through it will cause the neon gas to glow reddish-orange. So what is actually making the neon glow is the flow of electrons! Think of it as a visual way to watch electrons in action! Argon gas does the same thing, but glows in a pale blue. Argon also requires less voltage to excite it's electrons than neon. Usually we cannot really "see" how something works. With neon and argon gases you can.
Basic electricity teaches us three basic things:
- Voltage is the amount of "push".
- Amperage is the amount of "flow".
- Resistence inhibits or slows down "flow".
Because of this there is a certain threshold voltage or "push" that must be reached to excite the gas enough to make the electrons move and light up. Neon likes a lot of "push". That is how the electrons get moving along. Neon does not require a lot of "flow". No, you can't connect the end of an old extension cord to each electrode of a neon tube to get it to light. It won't work. Neon needs a much higher voltage. In my own experiments, I've found a voltage of 1K or one thousand is needed to even begin to excite the gas into glowing. Voltage requirements differ from tube to tube and sign to sign. Generally as a very liberal "rule of thumb" not written in stone, You need 1K of voltage for each 1 foot of tubing. Of course rules of thumb are not perfect. The larger the diameter of the neon tube, the more voltage is needed to light it properly.
Hopefully now you have a better understanding of just what goes on when that neon tube lights up! If you want to learn more, you can continue onto transformers.