how much time a 100w bulb takes to consume100w of energy?

Answer 1

Energy = power x time
The bulb rating of 100 watts is its power rating. The amount of time the bulb is on determines how much energy it uses. If the bulb is on for one hour, then the bulb uses 100 watt hours of energy. If the bulb is on for ten hours, then the bulb uses 1000 watt hours or 1 kilo-watt hour of energy.

Answer 2

I'm afraid this is a meaningless question because the watt is the unit of power, not the unit of energy. A 100W bulb consumes 100J (100 joule) of energy per second. That's what 100W means.

So "How much time does a 100W bulb take to consume100w of energy?" is meaningless but "How much time does a 100W bulb take to consume100J of energy?" has an answer – 1 second.

Another measure of energy, used in the electricity supply industry, is the kWh (kilowatt-hour). It is the energy consumed by a device operating at 1kW for 1 hour.

Using this unit you could ask "How much time does a 100W bulb take to consume1kWh of energy?" and the answer is 10 hours.

My old physics teacher used to say "If you understand the units, you understand physics."

Answer 3

Energy is measured in Whrs. So it'll take one hour to consume 100 Whrs of energy if that was your question.

Answer 4

1 hour