Physics Help Forum Two men or two nature?

 Apr 9th 2019, 05:34 PM #1 Senior Member   Join Date: Mar 2019 Location: cosmos Posts: 285 Two men or two nature? People have two concepts for electric current in physic now. 1. charges pass through unit surface in unit time. 2. The Maxwell replaement current. Nature should be be only one?
 Apr 9th 2019, 05:38 PM #2 Senior Member   Join Date: Aug 2010 Posts: 404 First of all, 'nature' doesn't define "electric current", people do. Secondly, there are many examples in which one concept has several equivalent definitions. There are always different ways of thinking about the same thing! topsquark likes this.
 Apr 9th 2019, 05:49 PM #3 Senior Member   Join Date: Mar 2019 Location: cosmos Posts: 285 Yes, nature does not define current, men do it. But current is a natural phenominon: it's charge moving..
Apr 10th 2019, 01:43 AM   #4
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 Originally Posted by neila9876 People have two concepts for electric current in physic now. 1. charges pass through unit surface in unit time. 2. The Maxwell replaement current. Nature should be be only one?
First off it's Maxwell's 'displacement current' not replacement current.

And yes there are two concepts for electric current because there are two different types of 'current' which occur in different circumstances.
Only one of these can be justifiably called

"movement of charge" as defined by

"charges pass through unit surface in unit time."

This first type of current is called conduction current and actually is 'carried' by moving charges.

In displacement current the charges do not move unless the current is alternating.

 Apr 10th 2019, 02:21 AM #5 Senior Member   Join Date: Mar 2019 Location: cosmos Posts: 285 Oh, yes...it's "displacement". Chen's first language is not English. Haha... If the capacitor is full charged, no movement of charge any more, the replacement current between the two panels will also be zero. Right? Last edited by neila9876; Apr 10th 2019 at 03:36 AM. Reason: correct word
Apr 10th 2019, 03:29 AM   #6
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 Originally Posted by neila9876 Oh, yes...it's "replacement". Chen's first language is not English. Haha... If the capacitor is full charged, no movement of charge any more, the replacement current between the two panels will also be zero. Right?
Why?

Capacitors pass alternating current as displacement current.

What actually happens depends upon the dielectric medium between the plates.

 Apr 10th 2019, 03:42 AM #7 Senior Member   Join Date: Mar 2019 Location: cosmos Posts: 285 Ok, follow what you are talking: When capacitor pass alternating current, are charges moving in the plates?
Apr 10th 2019, 04:10 AM   #8
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 Originally Posted by neila9876 Ok, follow what you are talking: When capacitor pass alternating current, are charges moving in the plates?
are charges moving in the plates?

not in and also not between, but into and out of.

 Apr 10th 2019, 04:09 PM #9 Senior Member   Join Date: Mar 2019 Location: cosmos Posts: 285 What's after "into"? It's "in". What's before "out of"? It's "in". What's behind those two concepts of current is the same natural phenominon: charge moving.
 Apr 10th 2019, 04:25 PM #10 Senior Member   Join Date: Apr 2015 Location: Somerset, England Posts: 1,035 You asked about charge moving in the plates. It doesn't. But if you know better why ask for an explanation ?

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