Emf induced in the windings of coil

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Homework Help Overview

The problem involves calculating the electromotive force (emf) induced in a tightly wound circular coil subjected to a changing magnetic field. The coil has 36.8 turns and a radius of 0.1 m, with the magnetic field increasing linearly over a specified time period.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants discuss the application of the formula for induced emf and the calculation of the rate of change of the magnetic field. There is an exploration of potential errors in the original calculation and the significance of the negative sign in the result.

Discussion Status

Some participants have confirmed the original poster's method as correct but have pointed out possible reasons for discrepancies in the answer, such as the need to report only the magnitude of the emf and issues with significant figures. The discussion is ongoing with no explicit consensus reached.

Contextual Notes

Participants are considering the implications of significant figures and the conventions for reporting the magnitude of the emf, which may affect the final answer.

dmckeog
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Homework Statement


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?


Homework Equations


emf=-N(dmagflux/dt)
dmagflux=dBA/dt
emf=-n*A*dB/dt
A=pi*r^2

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

 
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i really don't know what i have done wrong but the answer is wrong please help
 
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.
 
thanks a lot
 

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