Induced Emf in a Rectangular Coil

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  • #1
member 217843

Homework Statement


A rectangular coil of 90 turns has dimensions of 22 x 65 cm and is located in a uniform 1 T magnetic field. In 1.7 s, the plane of the coil is rotated from a position where it makes an angle of 19° with the magnetic field to a position where it makes an angle of 64°. Calculate the average emf induced in the coil.


Homework Equations



emf= -N*(d[itex]\Phi[/itex]/dt)
[itex]\Phi[/itex]=BAcos[itex]\vartheta[/itex]


The Attempt at a Solution



So I calculated the change in flux to be: (B*A*cos(90-64))-(B*A*cos(90-19)=B*A*(cos(26)-cos(71))

I then calculated emf.
emf= - ((90 turns)*(1 T)*(0.22m*0.65m)*(cos(26)-cos(71)))/1.7 s = -4.34 V
This is wrong. I then entered the absolute value, which is also incorrect.
 

Answers and Replies

  • #2
tiny-tim
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Hi SgtMousse! :smile:
I then calculated emf.
emf= - ((90 turns)*(1 T)*(0.22m*0.65m)*(cos(26)-cos(71)))/1.7 s = -4.34 V
This is wrong. I then entered the absolute value, which is also incorrect.

looks ok :confused:

have you tried 4.3 V, since it should be two significant figures ?​
 
  • #3
member 217843
Apparently my answer was correct, even though it was marked wrong. I just checked my online homework site, and they marked it correct. They must have had it wrong before. Thanks anyway!
 

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