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Homework Help: Under what conditions is a current generated w/ a magnet and solenoid?

  1. Jul 26, 2013 #1
    1. The problem statement, all variables and given/known data

    When putting a magnet into a solenoid, under what conditions is a current generated?

    3. The attempt at a solution

    In order for a current to be generated, the magnet needed to be moving as it passed through the solenoid. This is due to Faraday’s law, which states that an electric current can only be induced in a circuit through a changing magnetic field. By pushing the magnet through the coil of wire, the magnetic field is altered and a current is subsequently induced (also known as electromagnetic induction).

    Is this a correct explanation, or is there something more I should add? I can't help but feel like the answer is super short, but I'm not sure if there's anything else I'm missing. Thank you all so much!
  2. jcsd
  3. Jul 26, 2013 #2
    I think is correct but you should further use Lenz's law which will specify the direction of the current.
  4. Jul 26, 2013 #3
    EMF is generated across a coil when there is change in the magnetic flux associated with it. This EMF leads to a flow of current through a coil.
    The generated depends upon the rate of change of magnetic flux associated with the coil.

    EMF = d∅/dt

    Greater the speed of the magnet, greater the EMF generated and inturn, greater the current flowiwng through the coil.
  5. Jul 27, 2013 #4
    when the magnet falls through the coil a current will be produced according to Faraday's law as has been stated earlier .I wanted to add that this current will be such that(anticlock wise from top) it will create a magnetic field along the axis of the solenoid which will oppose the motion of the falling magnet itself.This is Lenz's law.So the magnet will experience a drag and if the solenoid is assumed to be long enough it will approach a terminal velocity.
  6. Jul 27, 2013 #5
    Thank you all so much! That makes a lot of sense, and I will include Lenz's law as well in my answer. A big thank you again!
  7. Jul 27, 2013 #6
    Anytime mate..!
  8. Jul 28, 2013 #7
    Best of luck
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