A Neon Sign Primer: How It Works and Why It Shines
Neon signs are more than just a pretty display of lights; they involve complex physics and chemistry to create their unique glow. In this blog, will provide you with a comprehensive understanding of the magic behind neon signs.
The Basics of Neon Sign Illumination
Neon signs work by passing an electrical current via argon-filled glass tubes. As argon reacts with ultraviolet light from mercury vapor lamps, it glows as a result of the electricity. When you see a neon sign in person, it appears that the gas is glowing from within—but this is not the case! Instead, the argon gas glows because its electrons are stimulated by the lamp’s UV light.
Types of Gases Used in Neon Signs
Helium – Helium is also a noble gas, however it has distinct properties than argon. Because helium has a very low boiling point, it requires less energy to heat up and produce light.
Argon – Because this gas is inert, it will not react with other substances or chemicals. It’s also non-flammable and chemically stable, making it suitable for indoor use and simple to keep clean.
Neon – It is a noble gas. It’s used in neon signs because it glows when electrified. This makes it ideal for lighting up signs, since it is one of the most visible gases.
Krypton – Because it has a larger ionization potential than argon, it can emit a brighter light. Krypton is also chemically inert and non-flammable, making it safer to employ in neon signs than other gases.
Main Components of a Neon Sign
GLASS TUBE: A tube filled with neon gas and sealed at both ends.
ELECTRODES: Electrode is placed at each end of the glass tube, connected to an alternating current source.
POWER SUPPLY: This converts the alternating current from the wall outlet into a direct current that flows through the electrodes in the glass tube.
How Electricity Flows Through a Neon Sign
Alternating current electricity travels through a neon sign. This means that, depending on the source of the current, electricity alternates directions and flows clockwise or counterclockwise.
The electricity enters the sign via an electrode (typically made of metal) and passes through an argon-filled glass tube. Electrons emit light when they clash with atoms in the tube, causing photons to be released (light particles). Light particles bounce off the tube’s sides and collide with additional atoms, releasing more light particles, and so on. This technique is repeated until a specified degree of brightness is obtained.
Excitation and De-excitation of Atoms in the Gas
Excitation is the absorption of energy by an atom, while de-excitation is the release of that energy. These processes in gases are essential because they can explain why gases have different properties than solids or liquids.
De-excitation happens when an excited atom loses energy by thermal radiation or spontaneous emission. Thermal radiation happens when an atom emits light as heat; spontaneous emission occurs when an atom emits light without receiving any energy.
Emission of Light in Neon Signs
In order to emit light in neon signs, there are three main components that need to be included: the gas, the electrodes and the glass tube. The gas is usually an inert gas such as argon or neon. The electrodes are made of tungsten and are powered by an AC voltage. The glass tube is sealed with a metal end cap at each end.
The electricity passing through the tungsten electrode strips electrons from it, which then travel down one side of the tube toward its positive end. When they reach this end, they collide with atoms from Argon or Neon gas molecules and cause them to release photons of light.
How Colors in Neon Signs Are Produced
The color of neon tubes can be changed by changing the gas mixture and the charge on the electrodes.
- Red: can be produced by using only argon and nitrogen gases in a tube.
- Orange and yellow: add mercury vapor to the tube.
- Green: add some helium and carbon dioxide to the mixture.
- Blue: add krypton gas.