- #1
shivanshu
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Why cathode rays which consist of electron that do not have any colour are seen as a colourful ray of light in a discharge tube??
In summary: I still can't understand please be more explanatory...In summary, the discharge tube often contains an inert gas to prevent the light from being emitted from the cathode and anode rays.
- #2
berkeman
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- #3
DrClaude
Mentor
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The OP appears to be asking about discharge tubes, not CRTs. The answer is because the tube contains a gas, and it is that gas that emits the light upon excitation from electron impact.
- #4
shivanshu
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That means that we cannot see the cathode and anode rays without any phosphor coating?berkeman said:
- #5
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shivanshu said:
Please read what DrClaude said. The discharge tube often has an inert gas!
Zz.
- #6
shivanshu
- 3
- 0
I still can't understand please be more explanatory...
- #7
berkeman
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We are all saying that an electron beam traveling in a vacuum does not give off a color of visible light. The energy from the accelerated e-beam can be transferred to phosphor or to gas molecules to cause visible light to be given off.shivanshu said:
Please use Google and our replies to do some more research on this topic, and report back here with links to your reading. Thank you.
- #8
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shivanshu said:
Electrons accelerates... bump into inert gas atoms... gas atoms get excited ... gas atoms then decay to give off light ... meanwhile, electrons get accelerated again... bump into other inert gas atoms ... gas atoms get excited ... gas atoms then decay to give off light ...
Zz.
1. What causes the coloured beam in a discharge tube?
The coloured beam in a discharge tube is caused by the emission of light from excited atoms or ions. When an electrical current is passed through the gas inside the tube, it causes the atoms or ions to become excited and emit light at specific wavelengths, resulting in a coloured beam.
2. Why do different colours appear in a discharge tube?
Different colours appear in a discharge tube because each element or gas has a unique set of energy levels. When the atoms or ions in the gas are excited, they emit light at specific wavelengths, which determine the colour of the beam. For example, neon gas produces a red-orange colour, while mercury gas produces a blue-green colour.
3. Can the colour of the beam be changed?
Yes, the colour of the beam in a discharge tube can be changed by using different gases or adding elements to the gas mixture. Each gas or element will have its own unique set of energy levels, resulting in a different coloured beam when excited.
4. What factors can affect the colour of the beam in a discharge tube?
The colour of the beam in a discharge tube can be affected by several factors, such as the type of gas or element used, the voltage and current applied to the tube, and the pressure and temperature of the gas inside the tube. These factors can influence the energy levels of the atoms or ions and therefore impact the colour of the emitted light.
5. Is the coloured beam in a discharge tube harmful?
No, the coloured beam in a discharge tube is not harmful. It is a result of low-pressure gas being excited by an electrical current and does not emit any harmful radiation. However, it is important to handle the discharge tube with caution as it does contain high voltages and can cause harm if not used properly.
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