1. Not finding help here? Sign up for a free 30min 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!

EMF problem - Current in Coil

  1. Apr 1, 2008 #1
    [SOLVED] EMF problem - Current in Coil

    1. The problem statement, all variables and given/known data

    A small square coil is located inside an ideal solenoid at the center with its plane oriented perpendicular to the axis of the solenoid. The resistance of this coil is 2.00 [tex]\Omega[/tex] and each side is 4.00 cm long. The solenoid has 125 windings per centimeter of length. If the current in the solenoid is increasing at a constant rate of 1.50 A/s, the current in the square coil is:

    a) steady at 18.8 [tex]\mu A[/tex]
    b) initially equal at 18.8 [tex]\mu A[/tex] but is increasing
    c) increasing at 1.50 A/s
    d) decreasing at 1.50 A/s
    e) zero

    2. Relevant equations
    [tex]\epsilon=\frac{d\Phi_{B}}{dt}[/tex]

    [tex]
    \Phi_{B}=BA
    [/tex]


    3. The attempt at a solution

    First, I plugged in what I know for magnetic flux:

    [tex]\Phi_{B}=BA=B(.04 m^{2})[/tex]

    Then I used that information to plug into the induced emf formula:

    And since

    [tex]B=\frac{N}{L}*i*\mu_{0}[/tex]

    Then

    [tex]\epsilon=\left|.04 m^{2}*\frac{N}{L}*\mu_{0}*\frac{di}{dt}\right|[/tex]

    where
    [tex]\frac{di}{dt}[/tex] is 1.5 A/S
    N = (125 *.04 m) = 5

    **

    My question is, am I going about this the right way? And if so, How do I find L and how can I use that to eventually get to the induced current?
     
  2. jcsd
  3. Apr 1, 2008 #2

    rock.freak667

    User Avatar
    Homework Helper

    Well [itex]\frac{N}{L}[/itex] is the number of turns per unit length. Which is given in the question. (Just convert the units)

    When you get the induced emf, use V=IR to find the induced current...
     
  4. Apr 1, 2008 #3
    Okay. (I thought L was inductance). I got a value, but how do I know if its increasing/decreasing, or steady?
     
    Last edited: Apr 1, 2008
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: EMF problem - Current in Coil
  1. EMF with coil (Replies: 10)

  2. Emf and coils (Replies: 6)

Loading...