Homework Help: Emf induced in the windings of coil

1. Jul 24, 2009

dmckeog

1. The problem statement, all variables and given/known data
a tightly wound circular coil has 36.8 turns, each of radius .1m. the uniform magnetic field is in a direction perpendicular to the plane of the coil. the field increased linearly from 0 to .42t in a time of .251s.
what is the emf induced in the windings of the coil?

2. Relevant equations
emf=-N(dmagflux/dt)
dmagflux=dBA/dt
emf=-n*A*dB/dt
A=pi*r^2
3. The attempt at a solution

dB/dt is rate I determined to be .42t/.251s=1.6733tpersec

emf=-36.8*pi*.1m*.1m*1.6733t per sec=-1.934v
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Jul 24, 2009

dmckeog

i really dont know what i have done wrong but the answer is wrong please help

3. Jul 24, 2009

Redbelly98

Staff Emeritus
Your thinking and method are correct. A couple of reasons why your answer might be rejected:
• They are just looking for the magnitude of the EMF, so no "-" sign is needed
• Wrong number of significant figures in the answer.

4. Jul 25, 2009

dmckeog

thanks a lot

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