What is Current (I) Measured Relative To

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What is Current (I) Measured Relative To

Postby DJ_Juggernaut on July 1st, 2018, 11:33 pm 

This is addressed to the locals: What is current measured relative to?

Lincoln » July 1st, 2018, 12:57 pm wrote:Current is frame-specific.

If we are talking about a current carrying wire. The current is wire-specific. It flows relative to a wire. If the relative velocity between the wire and the charges is zero. Current is zero. Any ammeter readily shows that current is wire-specific.

Lincoln wrote:If I have an infinite chain of positive charges, with density 1 coulomb/meter and I have them passing me at a rate of 1 meter per second, that's 1 Amp of current.

If a charge or charges pass by you, that's not a current. That's just moving charge or charges. Biot Savart law does not apply to you or to the charges that pass by you, it applies to a wire; as was the context we were discussing it in.

Anyone disagree with my statements? If so, why?
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Re: Surface Tension

Postby Faradave on July 2nd, 2018, 1:15 pm 

DJ_Juggernaut wrote:What is current measured relative to?

It's charge passing through some cross-sectional area (surface). As per Ben Franklin, positive charge for positive current. I put the definition on your earlier thread.
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Surface or observer?

Postby DJ_Juggernaut on July 2nd, 2018, 1:50 pm 

Faradave wrote:
DJ_Juggernaut wrote:What is current measured relative to?

It's charge passing through some cross-sectional area (surface). As per Ben Franklin, positive charge for positive current. I put the definition on your earlier thread.

I take it that you disagree with Lincoln's take that current is measured relative to an observer.
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Re: Area of Concern

Postby Faradave on July 2nd, 2018, 3:00 pm 

Let the cross-sectional area be the observer (detector) from which we read a measured current. If it moves with the current, no charge will pass through it, thus no current measured in that frame.
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Re: Area of Concern

Postby DJ_Juggernaut on July 2nd, 2018, 3:55 pm 

Faradave » July 2nd, 2018, 3:00 pm wrote:Let the cross-sectional area be the observer (detector) from which we read a measured current. If it moves with the current, no charge will pass through it, thus no current measured in that frame.

Sounds good to me.
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