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Calculating current from current density..

Posted Apr 17, 2015, 10:03 a.m. EDT Version 4.4 3 Replies

Aamir Qamar
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hello, could anyone help me how to calculate current from current density.
3 Replies Last Post Jun 1, 2015, 9:57 p.m. EDT
Lasse Murtomäki
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Posted: 9 years ago Apr 18, 2015, 12:06 p.m. EDT
Integrate over the area through which current flows.
Integrate over the area through which current flows.
Daniel Connelly
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Posted: 9 years ago Apr 19, 2015, 2:07 p.m. EDT
Not quite -- you need to integrate the normal component across the area, not the total current magnitude. Parallel components don't contribute to total current.
Not quite -- you need to integrate the normal component across the area, not the total current magnitude. Parallel components don't contribute to total current.
Aamir Qamar
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Posted: 9 years ago Jun 1, 2015, 9:57 p.m. EDT
Sorry for such a late reply. Actually I want to calculate current in a conductor but in comsol current density is given. As I am using magnetic electric interface so the current density is mef.Jx , mef.Jy, and mef.Jz in x, y and z direction. If the conductor is lying along x-axis so the area normal to the current density will be lying in yz plane.
The formula should be integrate(integrate(r*mef.Jx,r,0,rb),th,0,2*pi) as the mef.Jx is a constant numeric value the formula is simply equal to mef.Jx*pi*rb^2 . Now when I use any of the formulas to calculate current the value is high or low. Like I applied current of 5[A] at the center of the conductor so on one side the current according to the above formulas is 4.065[A] and on the other side it is -2.25[A]. Could anyone help what is the issue.
Sorry for such a late reply. Actually I want to calculate current in a conductor but in comsol current density is given. As I am using magnetic electric interface so the current density is mef.Jx , mef.Jy, and mef.Jz in x, y and z direction. If the conductor is lying along x-axis so the area normal to the current density will be lying in yz plane. The formula should be integrate(integrate(r*mef.Jx,r,0,rb),th,0,2*pi) as the mef.Jx is a constant numeric value the formula is simply equal to mef.Jx*pi*rb^2 . Now when I use any of the formulas to calculate current the value is high or low. Like I applied current of 5[A] at the center of the conductor so on one side the current according to the above formulas is 4.065[A] and on the other side it is -2.25[A]. Could anyone help what is the issue.

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