Posted by Physics on .
A 100W light bulb is left on for 10hrs. Over this period of time how much energy is used by the bulb?
am i doing this right?
my guess is to convert 100W to kW
and convert 10 hrs to seconds and multiply the 2 together?
which gives 3600J or should i just leave it in watts?

physics 
natali,
A 100W light bulb is left on for 10hrs. Over this period of time how much energy is used by the bulb?
am i doing this right?
my guess is to convert 100W to kW
and convert 10 hrs to seconds and multiply the 2 together?
which gives 3600J or should i just leave it in watts? 
natali 
drwls,
If you want the answer in Joules (wattseconds), multiply 100 W by 36,000 seconds.
If you want the answer in kilowatthours, multiply 0.1 kw by 10 hours. That's just 1.0 kwh. That would cost you about 15 to 20 cents from most utility companies these days.