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Voltage or current in solenoid?

  1. Dec 24, 2015 #1
    Hi everyone,

    I'm having some fun building solenoids for a project. I can't just leave "well enough" alone... I want to know how these things really work! I understand the concepts behind Faraday's laws, current in a wire, etc...

    What I would like to find out is which gives more force to the solenoid, V or I? I know Ohm's law says I can't raise one without the other... But does the force depend on the voltage or current, assuming the number turns remains constant?

  2. jcsd
  3. Dec 24, 2015 #2
    What "force" are you asking about? If you are asking about the induced magnetic field through the solenoid, then it depends solely on current. The equation is given by: B = μ n I, where μ is the magnetic constant (permeability of free space), n is the number of turns per unit length (turn density), and finally I is the current. Think of it like this: Movement of charges (current) induces the magnetic field, not the energy carried per charges (voltage). Hopefully this was the question you were asking, if it were not, then you might want to consider rephrasing the question.
  4. Dec 24, 2015 #3


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    The current is directly related to the magnetic field but, to cause a current to flow, a Voltage is needed.
    It's a matter of considering all the variables. n, the number of turns will affect the Voltage that's required to pass a given amount of current because the resistance of the length of wire affects the current. There isn't a 'heirarchy' of variables; they are all relevant.
  5. Dec 24, 2015 #4
    Thanks for your insight guys!

    The way both of you put it makes sense- current makes the field stronger, but the voltage is necessary to keep the current constant for a certain length.

    Thanks again!
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