Hi guy, I really need some help with this question (in preparation for the electric power explanation type SAC),
Explain why an alternator results in an AC output voltage? ...
My response was :
Faraday’s law states that the induced emf is equal to the rate of change of flux. As a coil initially rotates, it is on one particular side (take as positive), so as the maximum initial flux decreases to zero, (negative rate of change), a positive (according to Lenz’s law) voltage in induced.
After this, the coil is on the opposite side, and rotates from 0 flux to a maximum flux (in opposite direction, so is negative); this is a hence still decreasing flux, so a positive emf is induced.
Then, as the coil rotates from –max flux to 0, the rate of change of flux is increasing, hence inducing a negative voltage.
Therefore, as coil rotates from a positive to negative flux (and continues this cycle), flux both increases and decreases, so both a positive and negative flux is induced.
But I have been told this is wrong as flux is a scalar, and that it has something to do with the current? Can someone please clarify this for me? Thanks heaps