Question

An alternator provides 20 a of peak current at 100 volts peak ac to a resistive electric heater. how much heating power is delivered to the load?

Answer 1

Peak power is computed by: 20A x 100V = 2000 watts.
The heating power, is what you mean RMS, and if I suppose the wave form is sinusoidal. So,
the RMS is 0.707 of peak, so RMS voltage is 70.7 volts, RMS current is 14.14 volts, and RMS power is the product, or 1000 watts.