I bought this "flickering flame bulb" recently.

This is what it looks like: https://www.youtube.com/shorts/Py7pD0Oor9o

Here is the same thing but in slightly slow motion: https://www.youtube.com/shorts/bGrohhEwISg

I (a physics enthusiast) was talking about the bulb with my Dad (electrician) and we were arguing about how light is produced and why is it chaotic.

I'll from now on refer to the things inside the bulb as the "flame elements".

Here is my theory: It works the same way as a normal incandescent bulb. There is a vacuum inside the bulb. Current flows through some part of the flame element of the bulb then jump through the second half of the bulb and go to the ground. Current causes part of that "flame element" to emit light and increases its temperature. Because that part of the "flame element" is hotter it has higher resistance and that causes the current to change path - this is how chaos emerges.

Here is my dad's theory: It works similarly to fluorescent lamps. The bulb is filled with some sort of gas which is glowing when current flows through it. The "flame element" is not glowing at all it is gas around it that emits light. Chaotic behavior emerges because the bulb is powered by AC current and these changes in current flow are visible as chaotic behavior of the light inside the bulb. He also said that he thinks this means the chaotic behavior would be gone/bulb would not work if powered by DC current.

What I don't like in his theory is that the outer part of the "flame element" seems to be glowing. Why would current want to take such a long path from outside to outside instead of just jumping through the gap between the "flame elements" (shortest path)?

Here is the product page - it is unfortunately in Polish but maybe you could translate or derive something from photos.


Can u tell me who is right? If none of us is right what is the explanation?


1 Answer 1


Here is a summary of my understanding based on the materials attached in the comments.

Neither I nor my Dad is right (Dad was closer though).

The bulb is filled Mostly with Neon and a tiny bit of Argon. It is the gas that glows because it's excited by electricity.

The electrodes aka "flame elements" are too big for the applied voltage to glow on the whole surface. Because of intentionally too low voltage only part of the electrode glows. The chaotic behavior emerges because glowing gas differs in pressure from non-glowing one. More pressure equals more resistance (it is harder for electricity to go through already glowing gas) thus it seeks another path out (non-glowing area of electrode).

This pretty much answers my question.

Regarding AC/DC difference I found nothing on that topic.


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