Magnetic Field of Current

The magnetic field lines around a long wire which carries an electric current form concentric circles around the wire. The direction of the magnetic field is perpendicular to the wire and is in the direction the fingers of your right hand would curl if you wrapped them around the wire with your thumb in the direction of the current.

Calculation Bend current into loop
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Magnetic field concepts

Currents as magnetic sources
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Magnetic Field of Current

The magnetic field of an infinitely long straight wire can be obtained by applying Ampere's law. The expression for the magnetic field is

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For a current = Amperes and
radial distance = m,
the magnetic field = Tesla =Gauss.


The earth's magnetic field is about 0.5 gauss.

Index

Magnetic field concepts

Currents as magnetic sources
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Magnetic Field of Current

The magnetic field of an infinitely long straight wire can be obtained by applying Ampere's law. Ampere's law takes the form

and for a circular path centered on the wire, the magnetic field is everywhere parallel to the path. The summation then becomes just


Calculation

 Index

Magnetic field concepts

Currents as magnetic sources
  HyperPhysics***** Electricity and Magnetism Go Back