Puzzled about direct current and charge (flux)

  • #1

Main Question or Discussion Point

This is a question that has kept me awake, trying to rationalise it:

Current is rate-of-change-of-flux (or charge if you prefer, which is the same thing):
i = dQ/dt
Therefore, flux or charge is the time integral of the current.
Q = ∫i dt

Therefore, if you have a direct current, does this not imply that the flux/charge at a given point in the circuit keeps on growing indefinitely??
 

Answers and Replies

  • #2
Doc Al
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Therefore, if you have a direct current, does this not imply that the flux/charge at a given point in the circuit keeps on growing indefinitely??
No. The current in a circuit is the rate at which charge is flowing past a surface (or point).
 
  • #3
sophiecentaur
Science Advisor
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This is a question that has kept me awake, trying to rationalise it:

Current is rate-of-change-of-flux (or charge if you prefer, which is the same thing):
i = dQ/dt
Therefore, flux or charge is the time integral of the current.
Q = ∫i dt

Therefore, if you have a direct current, does this not imply that the flux/charge at a given point in the circuit keeps on growing indefinitely??
And how long could you keep this current flowing into a single point? The potential would pretty soon get so large that you couldn't continue. You are mis-interpreting the Maths.
 
  • #4
Ah, so my mistake was to say "the charge at a given point", when it should be "the charge that has passed a point", which of course can accumulate indefinitely!
 

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