How do fluorescent tubes light up with radio waves?

In summary, radio waves can cause gas in tubes to light up due to the interaction with the phosphor coating on the inside of the tube. The RF waves ionize the gas atoms, producing UV light which then hits the phosphor material and causes it to glow. This effect can also be achieved with gases that produce visible light, but the phosphors in the tube create a broader spectrum of light. The strength of the RF wave required for this effect is not easily determined, as it is affected by pressure and other factors. However, small inverters can be used to drive CCFL tubes and produce this effect.
  • #1
baconman71
25
0
I was reading somewhere that radio waves can actually light up gasses in these tubes. How does this work?
 
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  • #2
The gas isn't what actually lights. It is the phosphour coating on the inside of the tube. It works, I've done it.
 
  • #3
But it is the action of the RF waves on the atoms of the gas that produce the effect. If the peak field strength of the RF wave (alternating field) is enough to ionise the atoms then, when the electrons re-combine with the ions, UV is produced. This UV hits the Phosphor material on the sides of the tube and it fluoresces (glows).

You can get the same effect with some gases which produce visible light (e.g. the original Neon tubes) but it is coloured light. The phosphors on the side of the tube are a mixture of materials and in the solid state, which means that broad bands of visible light are produced. looking a bit like tungsten or sun light - much more useful.
 
  • #4
How strong does the peak field strength have to be in order for this to occur?
 
  • #5
It's not something that's simple to say since the ionization point of the gas is affected by pressure (refer to Paschen's curve). The small inverters that people commonly use to drive CCFL tubes for lighting effects have a sufficient voltage to capacitively couple through the glass and light a tube.
 

Related to How do fluorescent tubes light up with radio waves?

1. How do fluorescent tubes work?

Fluorescent tubes work by using electricity to excite the gas inside the tube, causing it to emit UV light. This UV light then hits the phosphor coating on the inside of the tube, which converts it into visible light.

2. What is the role of radio waves in lighting up fluorescent tubes?

Radio waves are used to energize the gas inside the fluorescent tube. They are emitted from a ballast or transformer and are responsible for creating the initial energy that excites the gas molecules.

3. How are radio waves able to energize the gas in fluorescent tubes?

Radio waves have a specific frequency that matches the resonant frequency of the gas molecules inside the tube. This causes the molecules to vibrate and produce energy, which excites the gas and creates UV light.

4. Do all fluorescent tubes use radio waves to light up?

No, not all fluorescent tubes use radio waves. Some tubes use other methods, such as electrodes or electric fields, to excite the gas and produce light. However, most modern fluorescent tubes do use radio waves.

5. Are there any risks associated with using radio waves to light up fluorescent tubes?

There are no known risks associated with using radio waves to light up fluorescent tubes. The frequency used is typically very low and poses no harm to humans or the environment. However, it is important to use caution when handling fluorescent tubes, as they contain small amounts of mercury which can be harmful if released.

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