Magnetism from electricity

Magnetism from electricity

• In 1820, Danish scientist Hans Christian Oersted discovered accidently that when electricity passed through a wire…a magnetic field was created

Which way would the compass needles point if we placed them around the wire?

Without a current….with a current

A magnetic field is induced by the current

Electromagnet

• A current carrying coil of wire with many loops is called an electromagnet

Superconducting electromagnetsThe most ignominious military use of superconductors may come with the deployment of "E-bombs". These are devices that make use of strong, superconductor-derived magnetic fields to create a fast, high-intensity electro-magnetic pulse (EMP) to disable an enemy's electronic equipment. Such a device saw its first use in wartime in March 2003 when US Forces attacked an Iraqi broadcast facility.

Magnetism and Electricity are related

Magnetism from Electricity• Many moving charges (an

electric current) produce a magnetic field

Electricity from Magnetism

Question of the day

If you can make a magnet from electricity, can you also make electricity from a

magnet?

Michael Faraday• It was largely due to his

efforts that electricity became practical for use in technology. His efforts created the “ancestor” of the electric motor and generators.

• Discovered electromagnetic induction (1831) ….which was a turning point in physics

Electricity from Magnetism

Current is induced by changing the magnetic field

• Consider that there is no power source, but if you move the magnet or move the wire…current in created

REVIEW

• Which moves to create current? The wire or the magnet?

Does this mean we get something (energy) for nothing?

• The law of conservation of energy states that the Force times the distance traveled = Work done…

• Work input = work output (or energy stored)

What can you do to create more current?

Faraday’s Law

1) Increase the # of loops2) Make the magnet or wires move faster

“The Great Revolution”…Einstein

• http://www.youtube.com/watch?v=TEVEBzNSwTU

• And part 2