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Induced EMF, finding current

  • Thread starter Defagment
  • Start date
  • #1
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Homework Statement



A coil with 253 turns of wire, a total resistance of 28 Ohms, and a cross-section area of 0.36m^2 is positioned in a plane perpendicular to the field of a powerful electromagnet.
What average current is induced in the coil during the 0.33s that the magnetic field drops from 2.2T to 0.0T? Answer in units of A.


Homework Equations



E = BA / t
V = IR

The Attempt at a Solution



EMF = Change in B * Area / time
= (2.2 * .36) / .33

I plug that into V = IR

V = IR
[(2.2 * .36) / .33] = I * 28 Ohms
I = [(2.2 * .36) / .33] / 28 = 0.0857142857A

However I get the wrong answer.
I think it has something to do with the 253 coils of wire but I'm not sure.
Any help is appreciated.
 

Answers and Replies

  • #2
648
2
Yes, the emf you calculate is induced in each coil of wire, so the total flux linkage at the start is BAN where N is the nuber of turns.
 

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