Magnetic Field Around a Wire, II

A handful of iron filings helps visualize the invisible magnetic field that circulates around a wire with a current running through it.

The magnetic field lines around an electrified wire 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 pointing in the direction of the current. This is known as the right hand rule.

The tutorial above uses an electric wire and a card with iron filings to reveal the magnetic field created by an electrified wire. Click the Turn On button to pass electric current through the wire. Notice how the filings indicate a circular magnetic field around the wire. The Current Direction arrow shows that the current is flowing from bottom to top. The current in the tutorial produces a Magnetic Field Direction around the wire that is counterclockwise, according to the right hand rule.

Last modified on 17 June 2019
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Magnet Academy is a free resource on magnetism & electricity brought to you by the Center for Integrating Research + Learning at the National High Magnetic Field Laboratory.