Energy usage on your electric bill is measured in kilowatt-hours (kWh). A typica
ID: 1347385 • Letter: E
Question
Energy usage on your electric bill is measured in kilowatt-hours (kWh). A typical American home uses about 1000 kWh a month.
a) What is the average power consumption of an American home, in Watts?
b) How many lightbulbs (60 W) would this light?
c) Does this seem reasonable? Think about the variety of things we power in our homes.
d) Instead of getting electrical power from a power plant, we could theoretically somehow use horses to power our homes. We would have to build a generator to convert the mechanical energy of the horse to electrical energy, but let’s pretend we’ve taken care of that. Converting energy the other way (electrical to mechanical) requires a motor. Both generators and motors are specific examples of transducers, things that convert energy between forms. How many horses would we need, at minimum (1 HP = 745 W)? Why might we want more?
Explanation / Answer
a) Average power consumtion, Pavg = Energytaken/time
= 1000 kWh/month
= 1000*3.6*10^6/(30*24*60*60)
= 1389 Watts
b) No of light bulbs can be lighten, N = 1389/60
= 23
c) No. we dont use these many light bulbs. we use other electrical equipments.
water heatter, refregertaor.. tec
d) no of horses needed = 1389/745
= 1.86 so apprximately 2
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