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# Magnetic field, in inches?

J

#### js5895

Jan 1, 1970
0
Hi,

Can I calculate the magnetic field around a wire in inches, I have
voltage and current.
Also, the magnetic field around a wire is cylindrical.

Thanks, for helping.

L

#### Larry Brasfield

Jan 1, 1970
0
js5895 said:
Hi, Hello.
Can I calculate the magnetic field around a wire in inches, I have
voltage and current.
Also, the magnetic field around a wire is cylindrical.

In air or vacuum, for an infinitely long wire, the strength
B of the magnetic field surrounding it at a radius r is:
B(r) = u0 * I / (2 Pi r)
where u0 is the permeability of free space (4e-7 * Pi),
B is in Tesla, r is in meters, and I is in Amperes. You
can do the conversions. The voltage is irrelevant.
The direction of the field is perpindicular to both the
wire and the normal from the given point to the wire.
This describes the static field for a DC current. For
AC currents and not r << wavelength, the above is
not the right equation, due to field propagation.
Thanks, for helping.
Welcome.

J

#### js5895

Jan 1, 1970
0
Thanks, but, I think I went over my head on this one.

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