Rate of Magnetic Field Change and current

  • #1

Homework Statement



A single conducting loop of wire has an area of 7.2×10−2m2 and a resistance of 120 ohms. Perpendicular to the plane of the loop is a magnetic field of strength 0.50 T.

At what rate must this field change if the induced current in the loop is to be 0.39A?

Homework Equations



emf=(-NdeltaIB)/(deltat)
Rate of change = emf/-N

The Attempt at a Solution



emf=(-NdeltaIB)/(deltat)
Rate of change = emf/-N

It's a single loop, so N should be 1
Rate of change - emf/-1

emf=v=IR

Rate of change = -IR
Rate of change = -(.39A)*120ohms=-46.8

This isn't right though.

Thanks for the help :)
 
Last edited:

Answers and Replies

  • #3
kuruman
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emf=(-NdeltaIB)/(deltat)

The correct equation is

emf = - dΦ/dt

where Φ is the magnetic flux through the loop which you need to calculate first.
 
  • #4
Arggh, I've been reading it as magnetic field, not flux. Thanks!
 

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