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# Capacitive AC circuit watch

1. Can anyone help me on this topic? I can't understand how to calculate by phase angle the fact that current leads voltage
the two equations:
V=V0 ?sin 2(pi)f*t
and
V=V(not) 2(pi)f cos 2(pi)ft

aorry, I don't know how to get it typed (Aaaargh!)
2. current is the rate of change of charge.
The charge on the capacitor at time t is proportional to the voltage across it at time t.
The first equation gives you the instantaneous voltage across the capacitor at time t.
You need to differentiate the first eqn with respect to time to get the equation for current at time t.

If you differentiate the sin of something you get???
3. Thanks
i differentiated the equation and got the answer.
differentiating sine gives cos. wrt time, differentiation of t gives 1.
Thanks a bunch!

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