I am getting confused with what area do you use in AC generators and coils.

Let me explain:

  • in an AC generator, there are two coils that rotate. When using the equation - magnetic flux $= BA\cos(x)$, when the area is perpendicular in the field, the emf induced within the coils should be 0. However, I keep getting the maximum emf and this is the same for coils too.

This is because I am using the cross-sectional area of the WIRE within the coil which is normal to the magnetic field.

However, should I actually be using the CROSS-SECTIONAL AREA of the COIL ITSELF (so like measuring the diameter of the coil instead of the diameter of the single wire)?? And if so, why would you use this area?

I don't know whether I am making myself clear, which is probably a sign that I really don't understand electromagnetic induction...

  • 1
    $\begingroup$ Maybe this post will help. $\endgroup$ Sep 23, 2020 at 12:04
  • 1
    $\begingroup$ Thanks! It really did! $\endgroup$
    – Phoooebe
    Sep 23, 2020 at 12:23

1 Answer 1


It is to measure the area of the coil itself, rather than the area of the individual wires. Thanks for the help!


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