P4 Magnets and Magnetic Field

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  • Created by: Sagaana
  • Created on: 02-05-18 13:45
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  • P4 Magnets and Magnetic Field
    • Magnets and magnetic fields
      • Magnets have a north pole and a south pole
      • They have magnetic field lines they closer they are the stronger the Magnetic flux density
      • You can see magnetic field line using compasses or iron filling (compasses all ways point north thus shows that the earth have a magnetic field
      • like pole repel and opposite poles attracts.
    • Electromagnetism
      • A current caring wire has a Magnetic field around it
      • If you have a lot of Solenoids together the magnetic effect increases
        • You can increase the magnetic effects of a solenoid:-current increased -the number of turns -the length of the solenoid-and adding a magnetic Core inside.
    • Magnetic Forces
      • When two magnetic fields affect one another . the result is a force.To experience full force the wire has to be 90 degrees to the magnetic field
      • Flemmings lefts hand Rule
        • Thumb: Motion
        • First Finger: Magnetic field
        • Second Finger: Current
      • Force= Magnetic Flux density x Current x Length
    • Motors
      • Current Increases so stronger Field and increases wire.which make the coil spin faster.
      • Split ring commutator keeps it spinning one way.
    • loudspeakers
      • Changing current in coil.the force on coil.The cone moves and the sound is made.
    • Electromagnetic induction
      • if you have circuit flow you can make electromagnets. this electromagnet has a field.The field opposes the motion.The moving wire and magnet will produce a P.D
      • Altenator
        • produce a a.c current and uses slip rings
      • Dynamo
        • Produce ad.c current and uses split rings
    • Transformers
      • they change the size of the potential difference.
      • they have two coils the primary and secondary.
      • an Iron is a magnetic material and the core becomes magnetised and it will
      • the changing magnetic field means that it will induce a p.d
      • Step-up transformer and step-down transformer

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