Question

A room heater is rated at 12 amps and 120vac. Electricity cost $0.12 per kWh. How much would it cost to run this for one month if it stayed on all of the time

Answer 1

The power of the heater is $P = I U = 12 A \cdot 120 V = 1440W = 1.44kW$.

The duration of a 30 day month is $t = 30 \cdot 24 h = 720 h$, hence the amount of energy the heater will consume if stayed on all the time is $1.44 kW \cdot 720 h = 1036.8 kW \cdot h$.

This will cost $0.12 \$ \cdot 1036.8 kW \cdot h \approx 124.42 \$.$