Magnetism

Magnets… Always have a North & South Pole The magnetic field is produced by the motion of electrons spinning in the same direction. In most substances, the spins cancel each other, but Iron electrons & a few others can be made to spin in the same direction, producing a magnetic field

Ferromagnetic A magnetic domain is a region that has a very large number of atoms with aligned magnetic fields. If a substance has this domain it can be magnetized. This substance is called ferromagnetic But being ferromagnetic does not mean it is a magnet When a material is magnetized, most of its magnetic domains are aligned

Magnetic Fields Magnetic Fields surround a magnet and can exert magnetic forces These fields are strongest near a magnetic pole

The magnetic field around the earth shields us from harmful radiation

Electricity and Magnetism Electromagnetic force: Electricity and magnetism are different aspects of one force. Moving electric charges create a magnetic field.

Solenoids and Electromagnets A solenoid is a coil of current-carrying wire that produces a magnetic field A solenoid with a ferromagnetic core is called an electromagnet Changing the current in an electromagnet controls the strength and direction of its magnetic field

The strength of an electromagnet depends on the current in the solenoid, the number of loops in the coil in the solenoid, and the type of ferromagnetic core. Increase the current – increase the strength Increasing the number of turns, leaving current the same, increases the field strength

Uses of Electromagnets An Electric Motor is a device that uses an electromagnet to turn an axle

MRI- Magnetic Resonance Imaging This device is used by doctors to create more detailed images of the human body than are possible with x-rays

Electrical Energy Generation And Transmissions Electromagnetic induction is the process of generating a current by moving an electrical conductor relative to a magnetic field

Faraday’s Law Michael Faraday’s law states that a voltage is induced in a conductor by a changing magnetic field This allows for the generation of electricity by power plants

Generators A Generator is a device that converts mechanical energy into electrical energy by rotating a coil of wire in a magnetic field. Two types of generators AC and DC Generators

Transformers A Transformer is a device that increases or decreases the voltage and current of two linked AC circuits A transformer changes voltage and current by inducing a changing magnetic field in one coil. This changing field then induces an alternating current in a nearby coil with a different number of turns

Transformers Step down transformers Step up transformers decrease voltage and increase current Step up transformers increase voltage and decrease current

Energy in our homes Most of the electrical energy generated in the U.S. is produced using coal Other sources of energy are water (hydroelectric), nuclear energy, wind, natural gas, and petroleum These generators have a large device with fanlike blades that turn when pushed. This device is called a turbine

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