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Induced EMF in Coil

(1/1)

Jefferson :
Does anyone know how to solve?

The source answer is A, people debating over B (because half a revolution produces 12V, then another half produced 12V to make 24V).

THSCStudyOnly:
I might be wrong here, but doesn't it produce 12V per one whole rotation?
Here is my reasoning:

emf = -N(d(Φ)/dt)
       = (-200(0.05 x 0.162)) / (1/46.8 )
       = -11.98V
       = (approx) 12V

And since I used 1/46.8 it should be one rotation produces 12V (because it takes 1/46.8s for it to spin one rotation)

Jefferson :

--- Quote from: THSCStudyOnly on October 03, 2019, 07:51:14 pm ---I might be wrong here, but doesn't it produce 12V per one whole rotation?
Here is my reasoning:

emf = -N(d(Φ)/dt)
       = (-200(0.05 x 0.162)) / (1/46.8 )
       = -11.98V
       = (approx) 12V

And since I used 1/46.8 it should be one rotation produces 12V (because it takes 1/46.8s for it to spin one rotation)

--- End quote ---

Sure, but the change in flux for half a rotation is
0.05 * 0.16^2. This is because it goes from 0 degrees to 180 degrees.
So for a full rotation, it should be 2 * 0.05 * 0.16^2

That's where the 24 is coming from.

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