When we pay the electricity bill, we pay for the
A) energy used.
B) power used.
C) voltage used.
D) current used.
Solutions: Option A
When calculating cost of electricity, we have to use E = Pt to find the electrical energy (kWh) used. Then we multiple by the cost of 1 unit of kWh (currently around $0.29).
In normal times, when finding electricity energy in joules (J), all physical quantities in E = Pt must be in SI units. (P in W and t in s).
Hence it is important to know that alternative units for electricity energy is kWh besides J.