The first useful electric magnet was created in England in 1825 by William Sturgeon. His 198gr electric magnet could lift 4.08 Kilogram, 20 times its weight. An electric magnet is basically insulated wire, usually wrapped around an iron core and then electrically charged. The electrical charge is what magnetises the wires. The stronger the charge and the more turns of wire used, the stronger the magnet. Electromagnets are used to demagnetise, hold and move objects. They can be found in many everyday objects.
Electric Motors and Appliances
An electric motor converts electricity into mechanical energy using electric magnets. The interaction between two sets of electric magnets creates a twisting force called torque. These motors, called AC induction motors, are used in many household appliances such as blenders, can openers, dishwashers, hairdryers, drills, washing machines and dryers. Any appliance or tool that requires quick turning will use electromagnets. Working on different principles, electromagnets are also responsible for controlling the intensity of the coils in a toaster and cooking food in the microwave.
Speakers and Microphones
Speakers in TVs, radios and stereos use electromagnetism to operate. Behind the speaker, there is a mobile electromagnet and behind that a fixed permanent magnet, one not electrically charged. The electromagnet is attached to the centre of the speaker paper or membrane. When an electrical current is sent through the coils, a magnetic field is produced, and the electromagnet is attracted and repelled by the permanent magnet, which causes vibrations. These vibrations are the sounds we hear through the speaker. A microphone does the opposite of a speaker; it catches sounds and turns them into electrical signals.
Electric magnets are heavily used in both the recycling and mining industries. In recycling, electromagnets are used to separate the many metal products we use, such as cans and batteries, from the non-metallic ones, such as papers and plastics. In the mining industry, after ore has been crushed, electromagnets are used to separate the metals and ore. The food industry also uses electromagnets to remove metal particles from foods. When heavy lifting is required, such as in the scrap metal industry, electromagnets are an invaluable tool.
Generators work in an opposite way to motors. Motors use electric magnets to turn electricity into mechanical energy, but generators use them to turn mechanical energy into electrical energy. The everyday electricity we use comes from coal, wind, water and steam, which turns a shaft, which then turns a set of magnets around a coil of wires, which produces electricity. A gas-powered car's alternator is a type of generator that takes mechanical power from a crankshaft and converts it to electrical energy, which powers the car's electrical system. The alternator also makes it possible for gas to run the motor.
- Whittington Village: William Sturgeon
- Universe Today: Uses of Electromagnets
- Math/Science Nucleus: Applied Science - Built Environment (4) Post Lab
- NASA: Electromagnetic Waves have different wavelengths
- Mister Fix it: Alternators - what are they, how do they work and what breaks
- Microchip: AC Induction Motor Fundamentals