Is it possible for an electrical device to generate more heat than another using less power or the same? People are claiming that a Plasma TV uses more power which explains why it uses more heat. We refer to power as wattage in this regard. Countering this, is it possible that a device can draw the same wattage or less and produce more heat? Basically, can something create more heat than something else with the same or less drawn power?
 A: Conservation of energy says that the sum of all energy in and out of a system must be equal to the change of internal energy of that system. So if you say that the system (say, your TV) remains in the same state (it doesn't get warmer over time), then the power in must equal the power out.
Now for an electrical device that gets all its power in through the electrical supply, there are broadly three different ways for power to come out.


*

*Heat

*Electromagnetic radiation (light, radio waves, etc)

*Work (rotation of a drill, motion of air from loudspeaker, elevator car being lifted, ...)


Very often, "heat" is an unwanted side effect of the conversion of electrical power into "something useful" - for example, an incandescent light bulb converts a lot of the power into heat, and only a little bit into visible light.
It is entirely possible that different devices will have different efficiencies, and will therefore produce a different amount of heat - it all depends what fraction of the electrical energy coming in is being converted to the other types of output.
For the case of the plasma TV, the mechanism for generating light is somewhat inefficient - see for example http://electronics.howstuffworks.com/plasma-display2.htm . Ionizing the gas so it can emit light requires quite a lot of power - so although the plasma TV excels in its range of intensities, color, and response time, all this comes at the expense of power consumption. By contrast, a LCD based screen uses a relatively efficient source of lighting (for example, LED or fluorescent lighting) and then uses the LCD to stop some or all of that light from reaching the viewer. So a LCD screen is "always on" - that is, always generating light - but for a dark scene it will re-absorb most of the light generated. A plasma screen will actually use less energy for a dark scene - it is simply not generating as much light to begin with.
A: For a device that is doing mechanical work of some sort, then the difference will be great.  As an example, an electric motor will draw a lot of power, but if much of that power goes into turning the shaft, then only some fraction is left to be dissipated as heat.
For a device that doesn't do any sort of similar work, then almost all of the input power goes directly into heat generation.  That's what you would expect for a television or computer.  In such cases, actual power draw would be an excellent measure of heat production.
But you'd need to measure it rather than go by the rating on the backplate.  That may give maximum values that are not representative of the power used during normal operation.
Presuming you're not talking about a heat pump (which moves heat around rather than only producing it), then the maximum amount of heat produced is equal to the power input.  A TV drawing 100W of power will be dumping 100W of heat into the room.
A: Our present heuristics suggest heat = motion. Let's see. When cities got dynamos and wires, fans became popular in homes and sweatshops. Later came light bulbs of course. If the armatures were not oiled the fans ran hot.Many fires etc. If motion can't do the intended work; it radiates as possible in the available medium. Hope that is easy for you.
