How many joules does A 100 watt light bulb consume in 24 hours?

Answer 1

You need to understand the difference between power - as in watts - and energy - as in Watt hours. Watts/kiloWatts only tells you what it's doing at the moment, at that very instant.

While Wh/kWh tell you the sum of what it's been doing over a certain time.

1 kW = 1000 w So 100 W / 1000 W = 0.1 kW

As soon at the light is turned on, the lamp starts to use energy at the rate of 100 W = 0.1 kW

If you leave it on for 24 hours it will have used up 0.1 x 24 = 2.4 kWh

Answer 2

100 watts means 100 Joules/Second. So in 24 hours, the bulb would use 24*60*60*100 Joules.

so that's 8,640,000 joules