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The motor effect

  • whn a current passes through a wire in a magnetic field a force may be exerted on it.
    • this is know as the motor effect


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Changing the force

The force can be effected by:

  • increasing the current 
  • using a stronger magnet
    • both increase force
  • changing the angle between the wire and field
    • greater when wire is perpendicular to the field
    • zero when they are parallel
  • the direction of the force is always at right angles to the wire and the field.
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The left hand rule


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The electric motor

  • uses the same priciples as the motor 
  • we control the speed of the motor by changing the current
  • we can reverse the direction of the motor by reversing the direction of the current.
  • the coil spins because:
    • a force acts on both sides of the coil in
    • the current goes in both directions due to the coil of the wire
  • the split rings alow it to spin in one direction, as it means the direction of the current changes every 1/2 a turn.
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The motor


(you don't need to know what a torque is, it's a good picture though)

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The Loud speaker

  • a Loud speaker is a coil that vibrates a diaphragm when an AC is passed  through it.
    • the motor effect causes the coil to move
    • because it's an AC it goes backward and forward causing it to vibrate.
    • (http://www.david-gouveia.com/gandalf/wp-content/uploads/2011/03/speaker-diagram-1-lables-flat-300x272.png)
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Electromagnetic induction

  • Opposite of a motor- a generator
  • it has coil moving in a magnetic field causing a current to start up.
  • they always create AC.


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  • A power station produces 25000v AC current,a house only wants 230v,on the national grid the voltage is 132000v

To change between we have transformers

  • an iron core has two coils wrapped around it when one coil has a current passing through it induses a current in the second
  • they only work for AC current.


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A transformer


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The national Grid

  • the higher the grid P.D. the greater the effiecieny of transfering electricity power through the grid.
    • this is due to the heat loss of a high current
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V= I x R


\frac{V_\text{s}}{V_\text{p}} = \frac{N_\text{s}}{N_\text{p}}.  (http://upload.wikimedia.org/wikipedia/en/math/b/b/4/bb4e12dfff1ebe6ed93aede98e283159.png) 

v= voltage N=number of turns S=secondary P=primary

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she said Rawr bro


Hiya, I don't know if it was just me, but the pdf file is unable to load, something about it being damaged and unrepairable? I wasn't sure if the problem was from my end or yours but I thought I'd let you know just incase (:

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