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Electricity Problem Solving

  1. Jan 10, 2006 #1
    I have this question that I have been completely stuck on with the equations that i have and i was wondering if someone could help me with this question but what equation should i use first to get myself going.

    Someone drives an electromagnet at a junk yard. Normally the magnet uses 200 A to lift a car of 360 kg, but now a force of 4200 N is required to lift a big old cadillac. What current would be required to make this lift?
  2. jcsd
  3. Jan 10, 2006 #2


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    Staff Emeritus
    Science Advisor
    Gold Member

    Perhaps you could start by showing us which equations you have to work with. Please share with us some of your thoughts and the work you have done. We can then guide you to a solution.
  4. Jan 10, 2006 #3
    This is what i have so far.

    I = 200 A
    Car Mass = 360 kg
    F = 4200 N
    Q= ?

    I'm looking for the current required to lift the car. The only equation i know that can find is Q= I delta t and Q=Ne but i don't see how any of those equations would help. If you see something i can't then show me what i should do.
  5. Jan 10, 2006 #4


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    Homework Helper

    First of all, Q refers to "Quantity of Electric Charge", not "Indicated Current".

    Do you know what causes a magnetic field in the electro-magnet?
    (hint: it is NOT electric charge ...)
    You're probably supposed to presume that the strength of the megnet
    is proportional to the quantity that determines the magnetic field.
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