Light - Photons - Electric Arc - Color

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ben sorenson

Joined Feb 28, 2022
106
I'm new to all this electricity stuff so bear with me as my questions could sound silly. I'm just trying to learn the interaction between things.

Let's say I had a basic circuit e.g 12 volts DC only consisting of an led and a resistor connecting one another with insulated aluminum wire and grounded to an aluminum bus bar.

I remove the "grounding wire" when the circuit is "live" obviously it sparks...the color of the spark is blue, if I reconnect it while still live the spark turns red, if I remove it again it turns green, if I connect it again it turns purple, and so on and so on down the spectrum of the rainbow. I haven't tried tried this, I'm just more so curious as to what gives the spark it's color between 2 metals. And would the color of the spark between 2 of the SAME metals ever change color? What if they did change color what would that mean, or why would it do that?
 

Irving

Joined Jan 30, 2016
3,190
I remove the "grounding wire" when the circuit is "live" obviously it sparks...the color of the spark is blue, if I reconnect it while still live the spark turns red, if I remove it again it turns green, if I connect it again it turns purple, and so on and so on down the spectrum of the rainbow.
Errr, apart from you won't get a visible spark with the current in that LED circuit, what makes you think the spark changes colour? A spark is the result of electricity 'jumping the gap' between two conductors through ionisation of the air - about 3000v per cm is needed - the colour of the spark is dictated mostly by the gas, but I guess the conductor metal might come into play as the heat of the spark melts it too. From my experience sparks tend to always be pretty much the same colour...
 
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