How does an electron gun shoot a stream of electrons?

In summary, the movement of electrons is what creates electricity. In a TV or monitor, an electron gun shoots streams of electrons through the air to hit a phosphor screen. These electrons are replenished by the AC power coming into the device. When an electron hits the screen, it triggers light emission, but the electron itself does not become light energy. The gun and the screen are connected in a circuit by high voltage DC, allowing for a continuous flow of electrons.
  • #1
Cyberice
50
0
Electricity is the movement of electrons from attom to atom but how are streams of electrons shot through the air to hit a phosphor screen in a TV or monitor by an electron gun? I have heard of electrical arc's but when those are preformed there are usually sparks going every where so I know it doesn't use an arch to reach the screen or to remove the elctrons from the atom.

I just don't see how an electron can be removed from it's atom to fly throught the air and make it to the screen. In electricity the same electrons are "recycled" over and over again throught the circuit by using the electron present in the conductor. But how the the atoms get their electrons back after having them shot off by an electron gun? How does the electron gun take away an atoms electron without replacing it with another one immetiately? How can you recycle the electrons once they hit the screen back into the atoms used for the electron gun? And where do the electrons go after they hit the phosphor to light it up? They obvioulsy don't build up, so do they just fall off? And to top off that pile of questions: Is the inside of a CRT a vaccum? Because if it isn't then how do the elements (gasses and dust) not interfere with the electons to prevent them from hitting the screen and using them for themselves?

I would LOVE to hear a good explanation to this.
 
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  • #2
Atoms loose and gain electrons all the time. When they have an unbalanced number they are called ions. This can occur through chemical means, electrical means, or just plain getting enough energy into an atom, such that the electrons are raised to an energy level allowing them to leave.

For example, in the circuit example you used - take a capacitor. Once the capacitor is charged, then part of the capacitor has too many electrons, thus a negative charge, the other a positive charge. They aren't balanced (or recycled as you put it) until the capacitor is discharged. Clouds can form a half of a giant capacity, which discharges in the form of lightning.

In the case of an electron gun, the guns element (similar to the filiment in a light bulb, is heated and kept at a high negative voltage. A screen not too far from the filiment has a high, but opposite charge, such that when the filiment is heated and the electrons have enough energy to escape they fly toward the screen. Their kinetic energy is enough to keep most of them traveling toward the picture screen. In this case, the vacuum of the picture tube is substituted for a wire. The net negative charge of the filiment is reduced by the leaving electrons, which travel to the screen, reducing it's net positive charge. Since circuits supply both the positive charge of the screen and the negative charge of the filiment, there is a flow of current from the filiment to the screen via the vacuum of the tube.

I'm sure I got many of the details incorrect, but the basics of how it works is enough to give you the idea.

Electrically charged particles (protons) form the solar winds, which cause the Auroras.
 
  • #3
Thanks for the info. I actually learned something. :smile:
 
  • #4
I live to serve. :wink:
 
  • #5
I know this is an older post post but thought you may be interested in more. To answer your questions (the best I can)
Yes, a CRT used in a TV or computer monitor is a vacuum.
The electrons from the "gun" are replenished by the AC power coming into the TV. This brings a constant source of new electrons.
Where does the electron go? You are right, it doesn't build up on the screen. When an electron hits the phosphor of the screen it becomes light energy. The light energy leaves the screen as light, not as an electron directly. This is extremely simplified, but gets the point across.
You should read here if you want to know more.
http://entertainment.howstuffworks.com/tv.htm
 
  • #6
The electrons may trigger light emission, but they do not 'become light energy' as in electron hits the phosphor of the screen it becomes light energy.

The gun and the screen are just two points along a circuit. The AC is converted to high voltage DC, the electrons travel fromt the DC source, into the gun, are shot at the screen, collected at the screen, and travel back into the DC source.
 

1. How does an electron gun produce a stream of electrons?

An electron gun uses a heated cathode to release electrons into a vacuum chamber. These electrons are then accelerated by an electric field towards a positively charged anode, creating a beam of electrons.

2. What is the purpose of an electron gun?

An electron gun is used in various technologies, such as cathode ray tubes in TVs and computer monitors, as well as in electron microscopes and particle accelerators. Its main purpose is to generate a focused beam of electrons for these applications.

3. How are the electrons in an electron gun controlled?

The electron gun has several components that help control the flow of electrons. The cathode and anode are charged with different potentials to create an electric field that accelerates the electrons. Additionally, there are focusing elements, such as magnetic lenses, that help shape and steer the electron beam.

4. What factors affect the performance of an electron gun?

The performance of an electron gun can be affected by various factors, including the temperature and material of the cathode, the strength of the electric field, and the design of the focusing elements. Additionally, external factors such as air pressure and temperature can also impact the performance of an electron gun.

5. How does an electron gun differ from a traditional gun?

An electron gun and a traditional gun may have similar-looking components, but they work on different principles. While a traditional gun uses chemical energy to propel bullets, an electron gun uses electric fields to accelerate electrons. Additionally, an electron gun does not require any physical ammunition and only produces a beam of electrons, making it a non-lethal technology.

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