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Dynamical Magnetism Faradays Law

  1. Apr 28, 2006 #1

    A fixed loop with Radius a and Resistance R is parrallel with the y-z plane. Another loop with radius r parallel to the y-z plane and a distance away from the other loop has a velocity v moving toward the other loop.

    What is the induced Voltage?

    Assuming (Told to assume this) a << r << x (Distance between loops)

    B = (UIr^2) / (2x^3) <--- Taken from physics book

    Flux = Integral B * n dA = Bpiea^2. (Flux thru fixed loop)

    Voltage = d(Flux)/dt = -piea^2d(B)dt = -(piea^2UIr^2)/2 d(1/x^3)/dt

    Problem... d(1/x^3)/dt = -3x^-4*v... I wasnt given x so how do I solve this?

    Voltage = (pie*a^2*U*I*r^2*3x^-4*v)/2 (I'm not given I or x) What am I doing wrong here.
    Last edited: Apr 28, 2006
  2. jcsd
  3. Apr 28, 2006 #2
    plz take notice. im dumb at physics... but from ur questions i see like 3 lines of equations(i dunno if they r related) . Like in maths question like that i would try solve it by simultaneously.
  4. Apr 28, 2006 #3


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    Staff: Mentor

    Induced voltage in what? Also, there is no B field mentioned in the problem statement, so there is no reason for there to be an induced voltage in anything. Is there a current flowing in the fixed loop, and you're asked to find the voltage induced in the second loop?
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