Unit 4 Day 1 – Magnetic Fields Produced by Electric Currents

• Magnets

• Magnetic Fields Surrounding Magnets

• Magnetic Fields Produced by Electric Currents

Magnets• Certain materials exhibit ferromagnetic

properties, ie: they are surrounded by a magnetic field

• Magnetic materials are: iron, nickel, cobalt, & gadolinium (and their alloys)

• Magnets consists of two ends called poles, referred to a north and south

• The magnetic field surrounding a magnet forms a closed loop through the magnet, in the direction from north to south

Magnetic Fields Surrounding Magnets

• A compass is used to determine the direction of a magnetic field.

• A compass needle always points away from the north magnetic pole

Magnetic Field Surrounding the Earth

• The earth consists of a magnetic field. • Note: The earth’s north-magnetic pole is at the south

geographic pole

Magnetic Field Between Two Magnetic Poles

• Magnetic fields between two wide poles of a magnet are nearly uniform with only slight fringing at the edges

• Magnets always consists of two poles

• Magnetic mono-poles do not exist in nature and have never been observed

Magnetic Fields produced by Electric Currents

• In 1820 Hans Christian Oersted found that a compass placed close to a current carrying conductor will deflect the needle

Magnetic Fields produced by Electric Currents

• An electric current produces a magnetic field around a wire. The direction of the field follows the Right hand Rule #1