• Created by: Lilycmxx
  • Created on: 27-03-20 13:22
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  • Electro-magnets
    • When an electric current flows in a wire, it creates a magnetic field around the wire.
      • This effect can be used to make an electromagnet
        • A simple electromagnet comprises a length of wire turned into a coil and connected to a battery or power supply.
    • Making an electro-magnet stronger
      • Wrap the coil around a piece of iron
      • Add more turns to the coil
      • Increase the current flowing through the coil
    • Advantages of Electro-magnets
      • They can be turned on and off
      • The strength of the magnetic field can be varied
        • The magnetic field around an electromagnet is just the same as the one around a bar magnet.
          • It can, however, be reversed by reversing the current (turning the battery around).
    • DC Motors
      • To make a simple DC Motor you need:
        • Two bar magnets
        • A coil of wire wrapped around something to support it
        • An axle for the coil of wire to spin around
        • two half rings (‘split rings’)
      • Motor Effect
        • Electric motors use the forces produced by magnetic fields to produce a turning motion.
          • If you put a length of wire in a magnetic field and pass a DC current through it (such as from a battery), the wire will move.
    • Electric Bell
      • The switch is open and the metal arm is away from the gong.
        • The switch is closed. An electric current flows through the electromagnet, producing a magnetic field.
          • The metal arm is attracted to the electromagnet
            • It hits the gong which makes a sound.
              • The circuit is broken and the electromagnet turns off.
                • The metal arm springs back. The contacts touch and the circuit is complete again.


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