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Homework Help: Basic Coil Turn question please see

  1. May 10, 2010 #1
    1. The problem statement, all variables and given/known data
    200-turn,coil of 8.0cm length is made of 0.50mm-diameter copper wire.
    Magnetic field is perpendicular to coil. At what rate B should increase to induce a 2.0 A current in the coil?

    2. Relevant equations

    3. The attempt at a solution
    i am not getting anthing
  2. jcsd
  3. May 10, 2010 #2


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    Hello helpphysics,

    Why don't start by stating any relevant equations, and then describe where and how you are getting stuck (showing your work as you go).
  4. May 10, 2010 #3
    i am sorry i am not getting it
    i just know that emf = A*∂B/∂t & thus
    2R = A*∂B/∂t
  5. May 11, 2010 #4


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    Hello helpphysics,

    I've been thinking about this problem a lot, and a couple of things are troubling me.

    Is this a homework problem?

    Is there anything missing in the problem statement, such as the radius, diameter, or cross sectional area of the coil? I see that the length is given. The length is useful if the coil is producing a magnetic field, but typically when discussing induced emf, something relating to the cross sectional area is given.

    Are there any other coils or solenoids involved in this problem?

    The problem statement says, "Magnetic field is perpendicular to coil." Initially I took this to mean that the cross sectional plane of the coil was perpendicular to the magnetic field (meaning the normal vector of the cross sectional area is parallel to the field). But thinking about it more, I think most people might interpret the problem statement as saying the major axis of the coil is perpendicular to the magnetic field. But if that was the case, there would be no induced emf at all! All I'm saying is that "Magnetic field is perpendicular to coil" is kind of a weird way to state the problem.

    The more I look at this problem, the more it seems that maybe something is missing. :confused:
    Last edited: May 11, 2010
  6. May 12, 2010 #5
    Sorry mate. No more info has been given.
    Don't worry you are not the only one going nuts over this. Physics is a hard nut! :tongue2:
  7. May 16, 2010 #6
    Anyway can you please help me out with the following?

    240V , 50 Hz electrical appliance is rated at 2 kW. It has a lagging power factor of 0.7
    (a) What is appliances power factor when it is used on a 60Hz supply.
    (b) What is supply voltage required to maintain appliance at its rated power when operated off a 60 Hz supply?

    Please look into this.
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