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Summary of Electromagnets

Summary of Electromagnets. Magnetic Fields and Electric Currents. A magnetic field is created around a wire with a current going through it. Direction of Field depends on the direction of the current. physics503.one-school.net. Strength of an Electromagnet. Strongest at the “Poles”

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Summary of Electromagnets

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  1. Summary of Electromagnets

  2. Magnetic Fields and Electric Currents • A magnetic field is created around a wire with a current going through it. • Direction of Field depends on the direction of the current physics503.one-school.net

  3. Strength of an Electromagnet Strongest at the “Poles” To add strength: • More coils • Closer together coils • More current (more voltage or less resistance) • Stronger ferromagnetic material ykonline.yksd.com

  4. 1. What is Electromagnetism? • The relationship between electricity and magnetism • electric current can make a magnetic field • a moving wire in a magnetic field can produce a current (electromagnetic induction) www.hk-phy.org

  5. 2. Characteristics of the Magnetic Field from an Electric Current • Direction of field can be changed - when direction of current is changed • Can be turned on and off (turn on and off current) • Strength can be changed www.cstephenmurray.com

  6. 3. Solenoids Solenoid: • Definition: a wire in a coil with a current • The ends of the solenoid act like the poles of a bar magnet

  7. 4. Electromagnets Electromagnet: • A strong magnet that can be turned on and off What is needed: • A solenoid (looped wire with a current) • Solenoid surrounding a ferromagnetic material

  8. 5. Solenoids and Magnetic Fields The magnetic field around an electromagnet is many times stronger than the magnetic field around just a solenoid. http://www.physics.sjsu.edu/

  9. 6, 7. Induction of an Electric Current • (6) Magnetic fields can create a current (called an induced current) in a wire when the wire (a conductor) moves through a magnetic field • (7) Either the magnet or the wire needs to be moving to induce a current The Cartoon Guide to Physics

  10. Direction of Current FYI • Changing the direction of the movement causes a change in direction of the current

  11. 8. Generators • Generators make electricity through electromagnetic induction • Mechanical energy transforms into electrical • Something moves the armature (a coil of wire) within a magnetic field and a current is produced in the wire (As the armature moves up the current is in 1 direction and as the armature moves down the current is the other direction) www.pbs.org

  12. Turbine • A turbine is a circular device with blades that turns an armature • When the wind/steam/water move the turbine the turbine will turn the armature (a coil of wire) through a magnetic field, which will induce an electric current geothermal.marin.org

  13. Induction of Current FYI • The current is induced – there is no voltage source (battery, wall socket…) • There is an induced voltage – which can be calculated using a formula (involving velocity, magnetic field strength and length of wire) • Once you have the voltage and the wire’s resistance, the current can be calculated using Ohm’s Law

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