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HELP Elctromagnetic Questions

  1. Jan 26, 2008 #1
    HELP !!!! Elctromagnetic Questions

    Ok I need to solve for Resistance, but itseems like I don't have enough info
    Here's my question :

    The rectangular wire loop has dimensions of 4.0cm by 3.0cm. Moving at constant
    speed, the loop completely exits the 0.14T uniform magnetic field in 0.12 seconds.
    The wire has a radius of 0.40mm and a resistivity of 2.15 x 10^-8 Ohm x m .

    Determine:

    A) the resistance of the wire

    Can you please help me with this ????
    I have exam on following monday SO i need to get this ASAP !
    THank you sooo much
     
  2. jcsd
  3. Jan 26, 2008 #2
    HELP !!!! Elctromagnetic Question

    Ok I need to solve for Resistance, but itseems like I don't have enough info
    Here's my question :

    The rectangular wire loop has dimensions of 4.0cm by 3.0cm. Moving at constant
    speed, the loop completely exits the 0.14T uniform magnetic field in 0.12 seconds.
    The wire has a radius of 0.40mm and a resistivity of 2.15 x 10^-8 Ohm x m .

    Determine:

    A) the resistance of the wire

    Can you please help me with this ????
    I have exam on following monday SO i need to get this ASAP !
    THank you sooo much
     
  4. Jan 26, 2008 #3

    pam

    User Avatar

    R=rho L/A. You know rho, L, and A.
     
  5. Jan 26, 2008 #4
    You can figure it out using the rules for magnetic flux and emf.

    [tex]\Phi = \iint \mathbf{B} \cdot d\mathbf{a}[/tex]

    which if the magnetic field is constant, then

    [tex]\Phi = B*Area[/tex]

    then the emf would be

    [tex]\epsilon = \frac{d \phi}{dt}[/tex]

    you can find the current with current density formulas and whatnot. Do some work, and we'll see how we can help you.
     
  6. Jan 27, 2008 #5

    mheslep

    User Avatar
    Gold Member

    Do you perhaps mean you need the impedance of the wire? Otherwise for resistance most of the given information about the shape of the wire (loop) is superfluous as Pam suggests. Only rho, L, A determine the resistance, the other information has no effect.
     
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