If you have ever read advanced textbooks or papers about electronics, you may have been surprised to see the use of complex numbers used in the analysis of AC circuits. A complex number has two par… ...

The more typical unit of energy for ac power circuits is watt-hours, Wh. In this case, t is in hours. If P is in kilowatts, kW, and t is in hours, J has units of kilowatt-hours, kWh.