Science PosseUniversity of Wyoming

Electricity and Magnetism

What is ELECTROMAGNETISM?

The fundamental relationship between electric fields and magnetic fields

Electromagnetism

A moving electric field creates a magnetic field that rotates around it

A moving magnetic field creates an electric field that rotates around it

The Right Hand Rule helps describe this

The Right Hand Rule

First define positive electric current as flowing from the positive (+) end of a battery, through an electric circuit, and back into the negative (-) end.

Next define a magnetic field as always pointing away from a North pole and towards a South pole.

The Right Hand Rule

Curl your fingers in the direction of the rotating field.

Extend your thumb. It now points in the direction of the other field.

If your fingers are curling along with a rotating electric field, your thumb will point in the direction of the magnetic field and vice versa.

The Right Hand Rule

The Electromagnet

By the Right Hand Rule, a coil of wire with current flowing in it will create a magnetic field

The strength of the magnetic field depends onThe amount of current in a wire – More current means stronger magnetic field

The number of turns in the coil – More turns means stronger magnetic field

The material in the coil – Magnetic materials like iron and steel make the magnetic field stronger

The ElectromagnetA simple electromagnet can be made by

coiling some wire around a steel nail, and connecting a battery to it.

As current rotates around the nail, a magnetic field is created with the North pole at the bottom and the South pole at the top

The Electromagnet

Electromagnets are found in many everyday objects such asMotors and generatorsDoorbellsSpeakersHard drivesVHS and Audio cassette tapesTelephones

The Electric Motor

An electric motor is a device that converts electromagnetic energy into mechanical energy

It works by using special electromagnets in the case of the motor that create North and South poles that are constantly spinning in a circle.

These spinning poles pull along magnets that are on the rotor (the part that spins), causing it to rotate

The Electric Generator

An electric generator works in the opposite of a motor; it converts mechanical energy into electromagnetic energy

An outside force moves magnets in a circle past several coils of wire.

By the Right Hand Rule, electric currents are developed in the coils of wire.