Graph of the EMF generated by an AC generator (1 Viewer)

[INnoVation]

Hello

Okay so I'm a bit confused about the graph of the EMF produced by a AC generator.
For phi/time, the curve of a AC generator I'm pretty sure is a sine curve.
Since an EMF is given by -n dphi/dtime, do I differentiate the sine curve to arrive at a cosine curve.
There is a negative in the equation which hasn't been account for, thus the final curve I arrive at for the EMF of an AC generator is a negative cosine graph.

May someone please help me with this, it's kind of getting on my nerves :/

 

[Squar3root]

It depends on the initial starting position

 

[anomalousdecay]

It depends on the initial starting position

Basically this.

You are not actually supposed to get the derivative (its HSC Physics), but in reality it is actually the derivative.