My question is this, an electrical heating coil, an LED light bulb, an incandescent light bulb, or an electric motor, say all run the exact same wattage of 500 watts at 120 volts. If you were to build a box around them and measure the heat over 1 hour would they all be equal?
Yes.
If the box is perfectly insulated, and opaque, then yes.
If the box is translucent or transparent, on the other hand, the light that leaves the box will mean energy leaving, and you will measure less heat with incandescent, and even less with the LED.
Thank you, that makes perfect sense.
And the motor will have vibrations that’ll be conducted outside the box, etc.
Point is, no box will be absolutely perfectly sealed (even the wires feeding that 500W into the whatever, will conduct heat, vibrations, etc., from inside to outside), so In Theory vs In Practice will be different, even a teeny-tiny ever-so-small bit. :laughing:
But in the end, it’s all pretty close?
I have a fish tank, the canister filter uses 23 watts, I can assume for the most part, except from the loss that leaves the tubes, and the body of the filter, I am probably putting a small amount of heat into my tank.
I was trying to explain to somebody the other day that a heating pad for a pet that uses 6 watts, is putting out far less heat than a 25w small light bulb would. I told him that a watt of energy no matter how its used makes the same heat whether it’s a light or a heater. I just wanted to make sure I was correct.
a tank is very different from a sealed box, 25w led lamp, or even a fluorescent will not heat your pet as 6w heating pad will, i assume it is not a fish that is in the tank, but some kind of a reptile. a pad would be much better heater, than a lamp, we can equate it with flood and spot light. lamp is a flood, that throws heat everywhere, but pad is a tightly focused light that heats up only a part that you need. where a pet sits. not to mention lamp will heat up upper portion of the tank, and hot air goes up, so bottom of the tank will not see much heat. for a pet in the tank, 6w heat pad where it sits, is much warmer than a 25w lamp above.
and if it is water in the tank, even more reasons for using a heater
Are you certain? Heat is the wasted energy and the various examples would have different efficiencies, right? So it seems different amounts of heat would be produced. Please correct me if this is not correct.
No.
If the tank is transparent and the energy is light, some will escape and not add any heat.
A motor that lifts something or put energy into a spring or flywheel will not generate heat for that energy.
You can also find some chemical reactions that will absorb energy
yea if you talking a 25w motor it would definitely make less heat than 25w bulb, unless you turn rotational power into heat,
a 100w inc bulb makes about 90w of heat, 100w el. motor makes only 10-15 watts of heat, the rest is rotational motion
Yes. In the end, all forms of energy will turn into heat.
Keywords: entropy, energy conservation law.
a spinning motor will not turn rotational power into heat. it will be just wasted by turning the shaft, not making heat. energy conservation is about all energy not just heat
It definitely is more complex than I thought. This is all very interesting! So maybe in a perfect world, in the sealed environment with insulation they’re all the same, but in the real world application, there are differences
A spinning motor WILL turn rotation to heat, no way around it.
Energy CANNOT be wasted, only as heat.
no it won’t. of course it can be wasted, heat is only 1 form of energy.
take a rock, and throw it, you just wasted energy, no heat produced, at least not even close to being equal of energy you spend throwing it
I disagree.
Chinese Watts are usually strongly exaggerated and rated higher 
no it won’t. of course it can be wasted, heat is only 1 form of energy.
take a rock, and throw it, you just wasted energy, no heat produced, at least not even close to being equal of energy you spend throwing it
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Wasted energy is usually converted heat, both a spinning motor and a thrown rock will convert the energy to heat (With the rock the final height above ground is part of the equation).
yea as far as your tank goes, unless it is a 25w inc par bulb shooting down the tank, heater will be a better option for heat.
even in a perfect world, mechanical energy is not turned into heat, heat is a byproduct of making mechanical energy. unless you intentionally turn it into heat. like we do every time we step on a a brake pedal, we turn mechanical energy into heat,
one can do a simple experiment, put a 25w bulb in a box and measure temp in 10 min, then do the same with electric motor consuming 25w, heat will not be even close to same
Does a 1,000W dedicated heater produce the same amount of heat as a 1,000W computer under load?
If so, then they both have the same heat production efficiency?