Easy question?

Which of the following is the best estimate of the energy used by a 100 W light bulb that is used to light a porch 12 hours per night for a month?

a. 4kWh
b. 40kWh
c. 400kWh
d. 4000kWh

I'm finding it somewhat difficult to make the connection between kilowatt hours with power in watts and time in seconds.

Answer:
lol you guys know you're helping a person most likely doing a open book test to pass. I hope this guy doesn't end up working on my house or building a bridge.

One KWh = a Kilo Watt for an hour:

100W = 0.1KW

Used for 12 hours = 1.2KWh

Used for 30 days = 36 KWh so the answer is b)

B.) 40kWh

Do the easy math..

100watts* 12 hours/day * 30days = 36000 W*hours

so the answer is b.) !!

I came up with 36 kWh so answer is b.

100 watts x 12 hours/day x 30 days/month = 36,000 watt-hours or 36 kilowatt-hours

I'm an engineer, and I've worked with a lot of engineers. I would prefer an engineer to ask someone if they are not sure how to calculate something than to guess and get it wrong. If its open book then they are using their resources wisely.

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