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Electromagnetics Help

  1. Dec 9, 2003 #1
    Hello! I'm looking for some hints or tips on a few problems in Electromagnetics. Everytime I approach a problem, I get frustrated and end up turning in crap. Then I find out the problems weren't so hard had I approached them differently. Anyhow, can anyone here help with this level of physics?

    Oh, please don't be insulted by my asking if anyone can help from this forum. Maybe I should ask if anyone will help. :smile: If you guys are willing to help, I'll post a few problems.

    Last edited: Dec 9, 2003
  2. jcsd
  3. Dec 9, 2003 #2
    Why don't you post a question & YOUR attempt at solving it, & maybe someone can show you the light.
  4. Dec 10, 2003 #3
    Yes we will help if you post your Que along with Try, but we want to see your attempt first even your thought process will help us to show u way
  5. Dec 10, 2003 #4
    Okay, here's the problem:

    Two infinitely long wires carrying currents [tex]I_1[/tex] and [tex]I_2[/tex]
    cross (without electrical contact) at the origin. A small rectangular loop is
    placed next to the wires, as shown below

    http://home.insightbb.com/~wxpunk/phys2.jpg [Broken]

    1. Obtain expressions for the B field at an arbitrary point inside the
    rectangular loop due to the two infinite wires. Hence write down an
    expression for the net B field at an arbitrary point inside the

    2. Obtain the magnetic flux ([tex] /Phi _B [/tex]) through the small rectangular
    loop (in terms of [tex]I_1[/tex], [tex]I_2[/tex], a, d, and b).

    3. If [tex] I_1 = I_0 cos /omega {t} [/tex] and [tex]I_2 = sin /omega t [/tex] determine the magnitude of the induced emf in the
    rectangular loop.

    4. On the same graph, sketch the time dependence of the induced emf,
    [tex]I_1[/tex] and [tex]I_2[/tex].

    5. Suppose [tex]I_1[/tex] and [tex]I_2[/tex] are constant, but the rectangular
    loop is moved away from the infinite wires at a constant velocity, v.
    Obtain an expression for the induced emf as a function of the angle of the
    constant velocity with respect to the x axis.

    6. What direction should the loop be moved in order to produce the maximum
    induced emf in the loop?

    I'm still working on the first part. Like I said, I get frustrated and don't
    know where to begin. This is the direction I'm going though...

    http://home.insightbb.com/~wxpunk/phys1.jpg [Broken]

    Please help, I'm lost! :frown:

    Last edited by a moderator: May 1, 2017
  6. Dec 10, 2003 #5
    The magnetic field from an infinite wire circles the wire (with a direction given by the right hand rule) and has a magnitude that is inversely proportional to the distance from the wire:
    B = \frac{\mu_0 I}{2\pi s}
    You have two infinite wires; why don't you try superposing their solutions first.
  7. Dec 11, 2003 #6
    I hope you have done the First problem with the above formulae

    For the second part calculate the flux due to I1&I2 Due to I1 it will be into the plane and due to I2 it will be outwards.

    You can consider the loop to be divided into small parts then aply the formula for flux

    \phi_1= \int_d^{a+d} \frac{\mu_0{I_1}}{2\pi x}dx

    If you have grasped it then we will move to next portion

    Attached Files:

    Last edited: Dec 11, 2003
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