# Formula Magnetic Field Outside a Current-Carrying Wire Magnetic field    Distance    Electric current

## Magnetic field

Unit
Magnetic field outside a long, current-carrying wire. The magnetic field runs circularly around the wire.

## Distance

Unit
Radial distance from the wire to a point outside the wire at which the magnetic field $$B(r)$$ is to be calculated.

## Electric current

Unit
Constant electric current flowing through the wire.