Electronics > Beginners
how exactly resistor works
tester43:
sooo.... i am happy to come back with "simple" question.
Resistor :)
What we know: "Ohm's law", "current limiting", "heat / power limit", "material difference in conductivity / amount of energy required to move the electron".
But:
* is the resistor a way to radiate overflow of energy as heat (wasted energy) - and that's how books are explaining it.
* is the resistor like a narrow tube between two large tubes limiting the water flow (no wasted energy).Which is is true?
glarsson:
If you push water through a narrow tube then the resistance the water "feels" is converted into heat. Also true for any other liquid or gas. One example is all the heat produced by a compressor or a simple bicycle pump.
taydin:
You can think of resistance like large diameter pipe, small diameter pipe. Or you can also think about a pipe with a polished internal wall, and a pipe with a rough internal wall. All work to imagine how a resistor would behave.
But a better analogy would be this: there are a heap of melons, and a group of workers want to load it onto a truck. So the workers form a line. The first one picks up a melon from the heap and gives it to the next worker in line. The last worker puts the melon on the truck. So there is a flow of melons, changing hand from one worker to the other.
Here, the flow of melons is "current", the manager shouting "come on guys, get moving!" is the "voltage", and the amount of laziness of the workers is the "resistance" ;D
rs20:
Just to perfectly clarify what glarsson is correctly pointing out;
--- Quote from: tester43 on September 28, 2018, 10:41:09 am ---a narrow tube between two large tubes limiting the water flow (no wasted energy).
--- End quote ---
The "no wasted energy" part is wrong. A narrow tube does dissipate energy.
--- Quote from: tester43 on September 28, 2018, 10:41:09 am ---But:
* is the resistor a way to radiate overflow of energy as heat (energy dissipated) - and that's how books are explaining it.
* is the resistor like a narrow tube between two large tubes limiting the water flow (energy dissipated).Which is is true?
--- End quote ---
Now that I've correct your question, the answer is "both".
hamster_nz:
--- Quote from: rs20 on September 28, 2018, 11:15:34 am ---Just to perfectly clarify what glarsson is correctly pointing out;
--- Quote from: tester43 on September 28, 2018, 10:41:09 am ---a narrow tube between two large tubes limiting the water flow (no wasted energy).
--- End quote ---
The "no wasted energy" part is wrong. A narrow tube does dissipate energy.
--- End quote ---
Can you explain this to me a little more? I can't resolve this in my head.
Unless the pipe is tapered (e.g. a nozzle) the same mass of fluid that enters the pipe exits the pipe, traveling at the same speed, so it is carrying the same energy, regardless of the diameter of the pipe.
The change of temperature of air as it is compressed is related to adiabatic processes.
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