Structure of Neon Lights
The structure of a typical neon light is shown in the figure.
Neon lights have two closely spaced electrodes that do not touch each other, arranged in a thick parallel line spiral or flat shape, sealed within a soft glass shell. The glass shell is filled with about 8 torr of neon gas. Additionally, a series resistor of about 2000 ohms is installed inside the cap.
When a high-voltage power supply is connected to the neon light, the cathode terminal begins to emit electrons. These electrons are accelerated by the electric field and collide with neon atoms. During the collision, some energy is transferred from the electrons to the neon atoms, exciting them. When the excited neon atoms and ions return to their ground state, they emit light.
Here are some key points about how neon lights work:
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In neon lights, the cathode is heated to emit electrons. For this, they require a very high voltage, depending on the distance between the electrodes.
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To discharge the neon gas, a voltage equal to 1.5 to 2 times the normal operating voltage is needed.
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The electric field strength near the cathode is very high, and ions gain significant momentum under the influence of stray fields, leading to cathode sputtering.
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A very small lamp current causes the gas to discharge flicker, while a higher lamp current produces a bright and stable discharge, but shortens the lifespan and causes the shell to blacken. Therefore, the lamp current for standard neon lights is less than 1 mA, or for high-brightness lamps, the lamp current can be as high as 2.5 mA.
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When using an AC power supply, each electrode alternates between being positive and negative. Thus, continuous illumination of the lamp can be achieved.
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Therefore, these types of neon lights are suitable for high operating voltage and low current applications.
A Brief History of Neon Lights
Heinrich Geissler (1857)
Geissler is considered the father of fluorescent lamps. His “Geissler tube” is a glass tube with electrodes at both ends, containing gas at partial vacuum pressure. He experimented with electric arc currents through various gases to produce light. This tube was the basis for neon lights, mercury vapor lights, fluorescent lights, sodium lamps, and metal halide lamps.
William Ramsay and Morris Travers (1898)
Ramsay and Travers created a neon lamp, but neon was extremely rare, making this invention not cost-effective.
Daniel McFarlan Moore (1904)
Moore commercially installed the “Moore tube,” which ran an electric arc through nitrogen and carbon dioxide to produce light.
Georges Claude (1902)
Although Claude did not invent the neon lamp, he devised a method to isolate neon from air, making the lamp affordable. The neon light was demonstrated by Georges Claude in December 1910 at the Paris Motor Show. Claude initially collaborated with Moore’s design but developed his own reliable lamp design and dominated the market for these lights until the 1930s.
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How do neon lights work?
Colorful, bright, and durable, neon lights are commonly used in signs, displays, and airport runways. How do neon lights produce different colors of light?
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Key Takeaways: A neon light contains a tiny amount of neon gas under low pressure. Electricity provides energy to strip electrons away from neon atoms, ionizing them. Ions are attracted to the terminals of the lamp, completing the electric circuit. Light is produced when neon atoms gain enough energy to become excited. When an atom returns to a lower energy state, it releases a photon (light). |
How to Make Neon Lights Yourself?
You can make a fake neon light yourself, but real neon lights consist of a glass tube filled with a small amount (low pressure) of neon gas. Neon is used because it is one of the noble gases. One characteristic of these elements is that each atom has a filled electron shell, so the atoms do not react with other atoms and require a lot of energy to remove an electron.
There is an electrode at either end of the tube. Neon lights actually work using either AC (alternating current) or DC (direct current), but if DC current is used, the glow is only seen around one electrode. AC current is used for most neon lights you see.
When a voltage (about 15,000 volts) is applied to the terminals, enough energy is supplied to remove an outer electron from the neon atoms. If there is not enough voltage, there will not be enough kinetic energy for the electrons to escape their atoms, and nothing will happen. The positively charged neon atoms (cations) are attracted to the negative terminal, while the free electrons are attracted to the positive terminal. These charged particles, called plasma, complete the electric circuit of the lamp.
So where does the light come from? Atoms in the tube are moving around, colliding with each other. They transfer energy to each other, and a lot of heat is produced. While some electrons escape their atoms, others gain enough energy to become “excited.” This means they have a higher energy state. Being excited is like climbing a ladder, where an electron can be on a particular rung of the ladder, not just anywhere on its length. The electron can return to its original energy (ground state) by releasing that energy as a photon (light). The color of the light produced depends on how far apart the excited energy is from the original energy. Like the distance between rungs of a ladder, this is a set interval. So, each excited electron of an atom releases a characteristic wavelength of photon. In other words, each excited noble gas releases a characteristic color of light. For neon, this is a reddish-orange light.
How Other Colors of Light Are Produced
Besides the orange-red of neon, there are two main ways to produce other colors of light. One way is to use another gas or a mixture of gases to produce colors. As mentioned earlier, each noble gas releases a characteristic color of light. For example, helium glows pink, krypton is green, and argon is blue. If the gases are mixed, intermediate colors can be produced.
The other way to produce colors is to coat the glass with a phosphor or other chemical that will glow a certain color when energized. Due to the wide range of available coatings, most modern lights no longer use neon but rely on mercury/argon discharge and phosphor coatings in fluorescent lamps. If you see a clear light glowing in a color, it’s a noble gas light.
Another way to change the color of the light, although it’s not used in light fixtures, is to control the energy supplied to the light. While you usually see one color per element in a light, there are actually different energy levels available to excited electrons, which correspond to a spectrum of light that element can produce.
Advantages of Neon Lights
The main advantages of neon lights are as follows:
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Neon lights can be made into miniature structures.
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Neon lights have instant illumination.
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Neon lights are inexpensive.
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These lights consume little power.
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They have a lifespan of up to 5000 hours.
Disadvantages of Neon Lights
The main disadvantages of neon lights are as follows:
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Neon lights are inefficient.
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Neon lights cannot be used for general lighting purposes, such as home lighting.
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Neon lights have a limited color range.
Applications of Neon Lights
The applications of neon lights are as follows:
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Neon lights are used as indicator lights, such as red lights for danger warnings.
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Neon lights are also used for advertising purposes.
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Neon lights are used in display applications to show letters, numbers, etc.
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Neon lights are used for decorative purposes.
References:
How Do Neon Lights Work?
How do neon lights work? Colorful, bright, and reliable, you see them used in signs, displays, and even airport landing strips. Here’s how they function and how different colors of light are produced.
Key Takeaways: Neon Lights
A neon light contains a tiny amount of neon gas under low pressure.
Electricity provides energy to strip electrons away from neon atoms, ionizing them. Ions are attracted to the terminals of the lamp, completing the electric circuit.
Light is produced when neon atoms gain enough energy to become excited. When an atom returns to a lower energy state, it releases a photon (light).
How Do Neon Lights Work?
You can make a fake neon sign yourself, but real neon lights consist of a glass tube filled with a small amount (low pressure) of neon gas. Neon is used because it is one of the noble gases. One characteristic of these elements is that each atom has a filled electron shell, so the atoms do not react with other atoms and require a lot of energy to remove an electron.
There is an electrode at either end of the tube. A neon light actually works using either AC (alternating current) or DC (direct current), but if DC current is used, the glow is only seen around one electrode. AC current is used for most neon lights you see.
When an electric voltage is applied to the terminals (about 15,000 volts), enough energy is supplied to remove an outer electron from the neon atoms. If there is not enough voltage, there will not be enough kinetic energy for the electrons to escape their atoms and nothing will happen. The positively charged neon atoms (cations) are attracted to the negative terminal, while the free electrons are attracted to the positive terminal. These charged particles, called plasma, complete the electric circuit of the lamp.
So where does the light come from? Atoms in the tube are moving around, colliding with each other. They transfer energy to each other, and a lot of heat is produced. While some electrons escape their atoms, others gain enough energy to become “excited.” This means they have a higher energy state. Being excited is like climbing a ladder, where an electron can be on a particular rung of the ladder, not just anywhere on its length. The electron can return to its original energy (ground state) by releasing that energy as a photon (light). The color of the light that is produced depends on how far apart the excited energy is from the original energy. Like the distance between rungs of a ladder, this is a set interval. So, each excited electron of an atom releases a characteristic wavelength of photon. In other words, each excited noble gas releases a characteristic color of light. For neon, this is a reddish-orange light.
How Other Colors of Light Are Produced
As far as colors go, how do neon lights work? You see lots of different signs with various hues, so you might wonder how this is achieved. There are two main ways of producing other colors of light besides the orange-red of neon. One way is to use another gas or a mixture of gases to produce colors. As mentioned earlier, each noble gas releases a characteristic color of light. For example, helium glows pink, krypton is green, and argon is blue. If the gases are mixed, intermediate colors can be produced.
The other way to produce colors is to coat the glass with a phosphor or other chemical that will glow a certain color when it is energized. Because of the range of coatings available, most modern lights no longer use neon, but are fluorescent lamps that rely on a mercury/argon discharge and a phosphor coating. If you see a clear light glowing in a color, it’s a noble gas light.
Another way to change the color of the light, although it’s not used in light fixtures, is to control the energy supplied to the light. While you usually see one color per element in a light, there are actually different energy levels available to excited electrons, which correspond to a spectrum of light that element can produce.
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