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Homework Help: What is the coils inductance?

  1. Nov 19, 2007 #1
    A coil has a resistance of 2.10 ohms. The potential difference across the coil is 11.6 V at an instant when the current through the coil is 5.00 A and is decreasing at a rate of 36.0 A/s. What is the coils inductance?

    I thought i could use the equation

    X=2pi fL to solve for L.. but i am confused as to whether or not 36.0 A/s is my frequency and if i can use 2.10 ohms as my X value. perhaps i am looking at it in the wrong way.
  2. jcsd
  3. Nov 19, 2007 #2
    :confused:Please help me out. Thank you.
  4. Nov 20, 2007 #3
    Induced emf is [tex]\epsilon=-L\frac{di}{dt}[/tex]

    So you can put it to Ohm's Law

    Potential difference across coil=Potential difference across resistor+emf
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