Electricity and Magnetism

1. Electricity and Magnetism Science Posse University of Wyoming

2. What is ELECTROMAGNETISM? • The fundamental relationship between electric fields and magnetic fields

3. 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

4. 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.

5. 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.

6. The Right Hand Rule

7. 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 on • The 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

8. The Electromagnet • A 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

9. The Electromagnet • Electromagnets are found in many everyday objects such as • Motors and generators • Doorbells • Speakers • Hard drives • VHS and Audio cassette tapes • Telephones

10. 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

11. 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.