Why does a plasma ball emit light?

[ahmeds]

TL;DR Summary

Plasma ball ligting

Is the cause of the lighting due to the impact of electrons with the nucleus

 

[berkeman]

TL;DR Summary: Plasma ball ligting

Is the cause of the lighting due to the impact of electrons with the nucleus

No.

https://en.wikipedia.org/wiki/Lightning

 

[ahmeds]

Can you explain why plasma ball emit light……….its long article in wiki i do not understand

 

[Dale]

The basic idea is that a high voltage produces and accelerates ions. Those ions collide with neutral gas molecules which becomes excited. When the excited gas molecule relaxes to the ground state, the energy from being excited is released as light.

 

[Baluncore]

Is the cause of the lighting due to the impact of electrons with the nucleus

No, not the nucleus.
To put it in non-physical language ...
The electric field in the plasma ball, tears electrons away from the outside surface of the gas atoms, leaving empty holes. The light is emitted when electrons fall back into those holes. The colour of the light is determined by the element and the depth of the hole.

 

[sophiecentaur]

No, not the nucleus.

Imo that's a bit sweeping. If there are ionised Hydrogen atoms about, there 'could' be an interaction with a proton (H+ ion / nucleus).
To be fair, though, the Lyman Series of spectral lines, which are due to electron / proton transitions are of invisible, very short wavelengths.
Visible lines tend to be produced from interaction with ions, other than Hydrogen, that are only partly ionised.

 

[Baluncore]

Imo that's a bit sweeping. If there are ionised Hydrogen atoms about, there 'could' be an interaction with a proton (H+ ion / nucleus).

This is not about any hydrogen ions that might be about.

Visible lines tend to be produced from interaction with ions, other than Hydrogen, that are only partly ionised.

To quote Wikipedia, the sphere is; "filled with noble gases, usually a mixture of neon, krypton, and xenon".

 

[sophiecentaur]

This is not about any hydrogen ions that might be about.

To quote Wikipedia, the sphere is; "filled with noble gases, usually a mixture of neon, krypton, and xenon".

We are discussing a real toy / cheap demo with a mixture of gases. It would be unlikely that the contents of the globe would be of high purity. The law of diminishing returns applies and this gadget has to sell at a reasonable price. The contents would be of similar purity to common or garden balloon gas. (Not so easy to come by these days.)

But my problem was with your categorical "no" about electrons hitting a nucleus. The "no" is a sweeping statement and could be mis-leading. That's all.

 

[Baluncore]

We are discussing a real toy / cheap demo with a mixture of gases.

That is correct. The gas mix is unimportant, so long as it works. Any UV emitted will not be "seen" directly, but may increase the ionisation of the plasma, which may then emit visible light.

But my problem was with your categorical "no" about electrons hitting a nucleus. The "no" is a sweeping statement and could be mis-leading. That's all.

This was a beginners question, so I went for understanding the basic principle. The "impact of electrons with the nucleus", needed to be clearly eliminated, before understanding the quantum physics of visible light.

 

[sophiecentaur]

This was a beginners question, so I went for understanding the basic principle. The "impact of electrons with the nucleus", needed to be clearly eliminated, before understanding the quantum physics of visible light.

Yes but a 'sufficient' answer would not usually be a minimalist answer. A beginner would surely need to have it pointed out that only one electron would be missing from an atom. That would mean that the collision would involve interaction with the nucleus and the rest of the electrons. It costs nothing to expand on the word "no", particularly when helping a beginner. We know that a recombining electron goes nowhere near the nucleus.

 

[Baluncore]

No.

It costs nothing to expand on the word "no", particularly when helping a beginner.

No, not the nucleus.

We know that a recombining electron goes nowhere near the nucleus.

YES.