Electrical energy units are often expressed in the form of kilowatt-hours. show that one kilowatt-hour (kwh) is equal to 3.6 x 106 j. if a typical family of four uses electric energy at an average rate of 520 w, how many kwh would their electric bill be for one month? how many joules would that be? at a cost of $0.12 per kwh, what would their monthly bill be in dollars? does the monthly bill depend on the rate at which they use the electric energy?

1) Family's monthly electrical consumption in kWh, E = 1518.4 kWh

2) Family's monthly electrical consumption in joules, E = 1.46624 x 10¹² J

3) Family's monthly bill, $ 182.21

4) Yes

Explanation:

Given,

The average rate of use of electric energy per person, P = 520 W

The average use of electric energy per person for a month, E = 520 x 730 Wh

                                                                                                       = 379.6 kWh

The family of 4 members uses the electric energy for a month,    E = 1518.4 kWh

Given that, 1 kWh = 3.6 X 10⁶ J

Therefore, the total energy in joules                      

                                          E =  1518.4 x 3.6 X 10⁶

                                             = 5.46624 x 10¹² J

The family's monthly electrical consumption in joules, E = 1.46624 x 10¹² J

The cost of 1 kWh = $0.12

Therefore, the total monthly bill

                                      1518.4  x 0.12

                                     = $ 182.21

The family's monthly bill, $ 182.21

The power depend upon the rate of doing work. If the power changes, the energy also change.

Yes, the monthly bill depends upon the rate at which they use electric energy.

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