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!

Rate of change of radius through a a circular wire loop?

  1. Apr 19, 2009 #1
    A circular wire loop of radius r = 19 cm is immersed in a uniform magnetic field B = 0.690 T with its plane normal to the direction of the field. If the field magnitude then decreases at a constant rate of −1.0×10^-2 T/s, at what rate should r increase so that the induced emf within the loop is zero?



    Flux=BAcos(theta)
    emf=dq/dt


    I tried this and I got an equation of 0=(Bcos0)(dA/dt)+(Acos0)(dB/dt)
    and I plugged it in to get dA/dt=.0016m^2/s and then i solved for the radius in this case which is .0228m and my answer is supposed to be in mm/s so i got 22.8 mm/s as my answer.
     
  2. jcsd
  3. Apr 19, 2009 #2

    rl.bhat

    User Avatar
    Homework Helper

    Area = πr^2.
    hence dA/dt = 2πr*dr/dt.
    Now find dr/dt.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Rate of change of radius through a a circular wire loop?
Loading...