How many kW*h (kilowatt hours) of electricity is consumed by a 500 w light bulb that burns for seven hours?

3.5 kWh

Explanation:

Given that the

Power P = 500 W

To convert watt to kilowatt, divide it by 1000

Power P = 500/1000 = 0.5 kw

Time t = 7 hours

Power is the rate at which work is done. That is,

P = WD/t

Cross multiply

WD = Pt

Where workdone WD is the energy E consumed in kWh .

Substitute P and t in the formula above.

E = 0.5 × 7

E = 3.5 kWh

Therefore, 3.5 kWh (kilowatt hours) of electricity is consumed by a 500 w light bulb that burns.

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b.a device that inputs heat into a cool object