Science Questions

Is there any matter in an electric current?

Sat, 2nd Oct 2010

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Humairaa Patel & Harold Pettus asked:

What is an electric circuit? Is there any matter in an electric current? Does it move?


There is matter flowing.  An electric current is a movement of electrons which are tiny particles.  They're very, very light compared to nuclei of atoms, so they're about 2/1000ths of the mass.  But they still do have mass.  They are matter and they're moving around. 

What happens in electric current is, essentially, you've got a conductor where these electrons can move quite easily.  You shove some electrons in, extra electrons in one end using a battery or a generator or something.  Electrons repel one another so that extra density causes all the other electrons to move away a bit.  And so, you get this sort of wave, essentially, you can think of it as a wave of movement, going all the way through to the other end of the conductor.

This wave of movement moves very close at the speed of light, maybe 0.8 of the speed of light, but the actual electrons themselves are only moving at millimetres a second.  So, the actual movement of electrons is very, very slow, but there is a movement.

The actual signal moves very quickly because it’s a bit like a Newton’s cradle where you hit a ball on one end, and then all the other balls transfer that impact all the way along, until the one on the other end flies away far quicker than any of the balls themselves are moving.


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Harold Pettus asked the Naked Scientists: Is there any matter in an electric current? What do you think? Harold Pettus, Fri, 1st Oct 2010

Electric current is composed of migrating electrons, and electrons do have mass, so it seems that there is matter in an electric current. Geezer, Fri, 1st Oct 2010

Yes matter is transported by the flow of an electric current hence electroplating and the early definition of the Coulomb syhprum, Fri, 1st Oct 2010

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