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: Average induced voltage

  1. Jul 25, 2011 #1
    1. The problem statement, all variables and given/known data

    A coil with 10 windings(radius 0,07m) is inside a homogenous magnetic(B=0,050T) field, it makes an angle of 90 degrees with the field lines so the magnetic flux is at it's max. Over a period of 0,050 seconds it gets turned by 180 degrees, what is the average induced voltage?

    2. Relevant equations

    Uinduced=-N* dphi/dt

    3. The attempt at a solution
    The area is 0.07²*pi= 0,015393804 m²
    So the magnetic flux in the situation before the turning is 0,015393804*0,050=0,0007696902 Wb
    (I dont normally write numbers like this)
    After it turns, this is the part i am unsure about, is the magnetic flux now -0,0007696902?
    because phi=B*cos(180)*A
    so the difference in magnetic flux is -2*(0,0007696902)
    Then Uinduced = -10 * (-2*(0,0007696902))/0.050 = 0,31 volts. Is this correct?

    I am verry sorry for my english. Thank you!
  2. jcsd
  3. Jul 25, 2011 #2
    Anyone? :-)
  4. Jul 25, 2011 #3


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    Welcome to Physics Forums.

    Yes, that looks good. I didn't check your arithmetic, but your procedure and reasoning are correct. The flux simply changes sign (+ to -) when the coil is flipped 180 degrees, so the change in flux is 2x the value of the flux.
  5. Jul 25, 2011 #4
    Thank you very much !
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook