How much heat do you get from a 75 watt lightbulb?

Answer 1

Depends on what you mean by "heat".

The entire 75 watts ends up as heat. Both the visible light and infrared radiated from the filament get absorbed by the surroundings and are converted into heat. So I would say the answer is 75 watts.

Sometimes, people use "heat" to mean non-visible, infrared radiation. From what I can remember, a typical bulb has about 85% of it's power radiated as infrared, so in that case it would be 85% of 75W = 64W.

Hope this helps.

Answer 2

At least 70 watts. An incandescent light bulb generates far more heat than light. A fluorescent lamp is about 4 times as efficient. Most efficient of all are LED lamps, consisting of red, green and blue LEDs which combine to give white light. These convert about 99% of the electrical energy into light. By comparison, when you're resting, you generate about 100 watts of heat.

Answer 3

It depends upon the efficiency and nature of the bulb.

for example...

A 75 watt fluorescent light bulb will produce less heat then a 75 incandescent bulb. (and more light if you apply the principles of the conservation of energy and momentum)

Answer 4

I agree with "genericman". Power of a bulb (75W in our case) is the consumed electric power. This entire power is inverted into radiation (heat). The light we perceive is only a little part of radiation, whose wavelength is in visible range.
Incandescent lightbulbs have efficiencies around 14%, that is to say, the useful energy (what we see as light) of a 75W bulb is about 11W. Anyway, this 11W light power, as well as the non-visible radiation power (66W) are all heat.

Answer 5

I agree with genericman. Since 1 watt = 3.412 BTU then 75 would give you 255.9.

Answer 6

Depends on the wattage applied.