1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Rogowski coils

  1. Mar 12, 2009 #1
    1. The problem statement, all variables and given/known data
    When a wire carries an AC current with a known frequency you can use a Rogowski
    coil to determine the amplitude Imax of the current without disconnecting the wire to
    shunt the current in a meter. The Rogowski coil, shown in the figure, simply clips
    around the wire. It consists of a toroidal conductor wrapped around a circular return
    cord. The toroid has n turns per unit length and a cross-sectional area A. The current
    to be measured is given by I(t) = Imax sin (ω t). (a) Show that the amplitude, E, of the
    emf induced in the Rogowski coil is E = μ0 n A ω Imax. (b) Explain why the wire
    carrying the unknown current need not be at the center of the Rogowski coil, and why
    the coil will not respond to nearby currents that it does not enclose.

    2. Relevant equations

    Emf= -N(dI/dt) where I = magnetic flux, not current

    Emf = I/R = R*(dQ/dt) where I = current

    Magnetic flux = *integral* (B*dA)

    Emf = *surface integral* (E*dL) = -(d*magnetic flux*/dt)

    Emf= (ANu/l)*(dI/dt)

    3. The attempt at a solution
    I am not really sure where to start - maybe by using the Emf= (ANu/l)*(dI/dt) ?? Can anyone help get me started in the right direction? Thanks!

    **In the attached document, the diagram is in #6, all the way at the bottom**

    Edit: The figure is simply a ring of wire that has another wire wrapped around it, with a current going through the ring. Apologies for the mix up
    Last edited: Mar 12, 2009
  2. jcsd
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted