Induction Laws and alternators Flashcards Preview

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Flashcards in Induction Laws and alternators Deck (11):

What is Farday's Law?

  • the induced emf is directly proportional to the flux linkage
  • ε = N ΔΦ / Δt


In a graph of flux linkage against time, what is the gradient?


In a graph of magnitude of emf against time, what is the area under the curve?

  • gradient
    • size of emf
    • if the line is flat, gradient is 0 and no emf is induced
  • 2)
    • area under curve is flux linkage change


What is Lenz's Law?

  • induced emf is always in such a direction as to oppose the change that cause it


How are Lenz's and Faradays Law combines?

  • ε = - N ΔΦ / Δt
  • - flux linkage change / time taken




Why is a minus used in the combined equation


  • shows the direction of the induced emf




How is Lenz's Law basically conservation of energy?

  • energy used to pull a conductor through a magnetic field, against the resistance caused by magnetic attract, is what produces the induced current


How can Lenz's law be used to find the direction of an induced emf and current in a conductor travelling at right angles to a magnetic field


What is an alternator?

  • generator of alternating current




What is a dynamo?

  • i.e. generator
  • conver KE to electrical nergy - induce an electric current by rotating a coil in a magnetic field



How is an alternating current produced by a dynamo?

  • output voltage and current change direction with every half rotation of coil


  • Induced current such as to opposes the change producing it
  • Switch on - current increases the flux through Y
  • Current opposite direction/anticlockwise to create opposing flux
  • Switch off - flux thorough Y due to X decreases so current travels clockwise to create flux to oppose the decrease