A microwave oven has a power requirement of 1,245 W. A frozen dinner requires 4.8 min to heat on full power. (a) How much electrical energy (in kWh) is used? kWh

Question

This is the second part of the question.

(b) If the cost of electricity is 10¢ per kWh, how much does it cost to heat the dinner? (Do not round your final answer. Fractional cent values are acceptable.)

¢

Answer 1

As the unit of used energy is kWth, you need to convert minutes into hours.

4.8 minutes =4.8min/(60 min/h)=0.08 h

Next, energy=power times time, that is, E=Pt=1.245 kW*0.08 h=0.0996 kWh

The cost will be product of unit cost and spent energy: 0.0996kWth*10cents=0.9966 cents