# Static Magnetic Fields and Effect on ESR

D

#### D from BC

Jan 1, 1970
0
I have a goofy question and I can't find my old college physics
books..

When two identical repelling electromagnets are brought close
together, does the DC current change?

Details
* Constant V across e-magnets
* Assume no wire heating effects
* The DC current is measured when the electromagnets are motionless.

Q2:
Do different levels of DC across a toroid inductor affect the ESR?
(Assume no wire heating effects..)
D from BC

J

#### John Larkin

Jan 1, 1970
0
I have a goofy question and I can't find my old college physics
books..

When two identical repelling electromagnets are brought close
together, does the DC current change?

Details
* Constant V across e-magnets
* Assume no wire heating effects
* The DC current is measured when the electromagnets are motionless.

The current changes transiently as they are brought together...
increases I think. Then it decays exponentially back to the original
Q2:
Do different levels of DC across a toroid inductor affect the ESR?
(Assume no wire heating effects..)

Depends on your definition of ESR, but if you mean AC impedance, for a
ferrous core, yes. For an air core, no.

John

M

#### MooseFET

Jan 1, 1970
0
The current changes transiently as they are brought together...
increases I think. Then it decays exponentially back to the original

Lense's law implies an increase.

Depends on your definition of ESR, but if you mean AC impedance, for a
ferrous core, yes. For an air core, no.

I think there is a small increse in the DC resistance too. It is
unlikely that you will ever see it in a real situation but perhaps at
some extreme it will show up. The electrons flowing in the copper
will have their paths deflected slightly by the field.

J

#### jasen

Jan 1, 1970
0
I have a goofy question and I can't find my old college physics
books..

When two identical repelling electromagnets are brought close
together, does the DC current change?

Details
* Constant V across e-magnets
* Assume no wire heating effects
* The DC current is measured when the electromagnets are motionless.

Seeing as it's you, (and not another homework question) I won't take it
literally.

If I can also ignore any magnetostrictive effects and only measure the
steady state (and not what happens immediately after the magnets stop moving)
Q2:
Do different levels of DC across a toroid inductor affect the ESR?
(Assume no wire heating effects..)

no, but it can effect inductance if it's saturable.

Bye.
Jasen

D

#### D from BC

Jan 1, 1970
0
Seeing as it's you, (and not another homework question) I won't take it
literally.

If I can also ignore any magnetostrictive effects and only measure the
steady state (and not what happens immediately after the magnets stop moving)

no, but it can effect inductance if it's saturable.

Bye.
Jasen

Yeah...I know its a homeworky type question...

I didn't think static magnetic fields significantly affect wire
current density but wasn't sure...
(Ex..permanent magnet resting on a wire. )

For example...
I"ve never heard if wire conducts more (or less) at the north pole.
(neglecting temperature effects )
Could be the start of another speaker wire myth...
Better sound at the North pole...

D from BC

J

#### John Larkin

Jan 1, 1970
0
I think there is a small increse in the DC resistance too. It is
unlikely that you will ever see it in a real situation but perhaps at
some extreme it will show up. The electrons flowing in the copper
will have their paths deflected slightly by the field.

I suppose that happens in a straight conductor in free space too, a
sort of spiral electron path due to Hall effect. So Mr Ohm was wrong
after all!

Gosh.

John

J

#### John Larkin

Jan 1, 1970
0
Yeah...I know its a homeworky type question...

I didn't think static magnetic fields significantly affect wire
current density but wasn't sure...
(Ex..permanent magnet resting on a wire. )

There would be a Hall potential developed in the wire at certain
magnetic field orientations, and that could increase resistance
slightly. I don't know if it's enough to measure, probably not.

For example...
I"ve never heard if wire conducts more (or less) at the north pole.
(neglecting temperature effects )
Could be the start of another speaker wire myth...

Yup, Hall Effect Harmonic Distortion. You heard it here first.

John

D

#### D from BC

Jan 1, 1970
0
There would be a Hall potential developed in the wire at certain
magnetic field orientations, and that could increase resistance
slightly. I don't know if it's enough to measure, probably not.

Yup, Hall Effect Harmonic Distortion. You heard it here first.

John

lol
D from BC

R

#### Robert Latest

Jan 1, 1970
0
John said:
I suppose that happens in a straight conductor in free space too, a
sort of spiral electron path due to Hall effect.

What you mean is the Lorentz force which in turn causes the Hall effect.

robert

P

#### Paul Hovnanian P.E.

Jan 1, 1970
0
John said:
There would be a Hall potential developed in the wire at certain
magnetic field orientations, and that could increase resistance
slightly. I don't know if it's enough to measure, probably not.

Yup, Hall Effect Harmonic Distortion. You heard it here first.

Great. Another market for my cow magnet business. The gas mileage boost
scam was getting a bit old.

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