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Electricity from Magnetism

Electricity from Magnetism. If we can get motion from electricity, can we get electricity from motion??. Current – is induced in a conductor when the conductor moves through a magnetic field!. c alled Electromagnetic Induction ! The current induced - Induced current

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Electricity from Magnetism

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  1. Electricity from Magnetism If we can get motion from electricity, can we get electricity from motion??

  2. Current – is induced in a conductor when the conductor moves through a magnetic field! • called Electromagnetic Induction! • The current induced -Induced current • Either the conductor moves – mag. Field, or the magnetic field moves thru conductor. No battery needed!

  3. What is DC? • Direct current - charges that flow in one direction. Battery good example

  4. What is AC • Alternating Current – charges that move back and forth in a circuit. Current in homes, schools, work, etc. is in this form. • Major Advantage – voltage can be raised or lowered according to your needs. High – travels long distances, low – bring into home.

  5. What is a generator? • A device that changes mechanical energy into electrical energy. ..Movement – makes current • (just the opposite of a motor) • AC generator –turn crank, armature rotates in the magnetic field, the wire has an induced current. The wire – goes thru N then S, then N so electrons begin to flow! There is an armature, brushes, perm magnets and slip rings instead of commutator.

  6. What is a DC generator? • This is the same as a dc motor except rather than use electricity to move a motor, you move the motor to get electricity!

  7. Using generators • Electrical companies use turbines or a cylinder with many blades to turn an armature inside of many magnets. The armature or wires pick up the magnetism from magnets and they undergo N, then S, then N, then S mag. Fields.

  8. What is a transformer? • A device that increases or decreases voltage. • Two separate coils around an iron core. The primary coil is connected to voltage source. The secondary coil is connected to separate circuit without voltage.

  9. How do they work? • The primary coil produces a magnetic field, which is picked up by a piece of iron. This mag. Field (which is changing) induces a current in secondary coil. Has to change mag. Fields or the current is not induced in secondary coil. Does not work with DC.

  10. Step up transformer • Increase voltage ..the secondary coil has more loops.

  11. Step down transformer • Reduces the voltage • The secondary coil has less loops than primary

  12. How are transformers used? • To transmit current over long distances, we must have a high voltage. So . .you would use a step up transformer out of power plant. • To use safely in our home, you must have a low voltage so a step down would be used. • Some machines need higher voltage to operate than what we have in home. TV, x-ray machines, fluorescent lights. • Doorbells, portable cd players need low voltage

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