Energy consumption ?

Question

how much energy does a 100w light bulb use in an hour?

Answer 1

1 watt = 1 joule/second

so 60minutes*60seconds*100 watts =360000joules=360 kj of energy?

Answer 2

100 x 3,600 = 360,000 joules

360 kJ = 1 kWh (kilowatt hour)

Answer 3

Absolutely 100 Wh

Answer 4

If it is incandescent then about 4 times as much as a CFL with the same brightness.

Answer 5

Electricity use for billing purposes is measured in kilowatt hours. One 'unit' is one kilowatt hour. A kilowatt is 1000 watts, so your 100 watt lightbulb would use 1/10 of a unit. My last electricity bill charged me 8.75p per unit (before VAT), so it would cost just under 1p to leave a 100w light on for 1 hour.