Induction Laws and alternators Flashcards Preview

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Flashcards in Induction Laws and alternators Deck (11):
1

What is Farday's Law?

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

2

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

3

What is Lenz's Law?

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

4

How are Lenz's and Faradays Law combines?

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

 

 

5

Why is a minus used in the combined equation

 

  • shows the direction of the induced emf

 

 

6

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

7

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

A image thumb
8

What is an alternator?

  • generator of alternating current

 

 

9

What is a dynamo?

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

 

10

How is an alternating current produced by a dynamo?

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

11

Q image thumb

  • 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