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sophiecentaur
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Very picturesque but my physical appreciation is a bit overwhelmed with mental images of the flora and fauna in this mountainside canal.
You seem to think that electrons are little packets of energy that are delivered to the load. That's false. You are jumping all over the place, from thermionic emission to the power grid.Chan Pok Fung said:Combining the above thoughts, I propose two possibilities where both contradicts to reality.
Here's an easy 'mechanical' argument that tells you the Kinetic Energy of electron motion is actually irrelevant. Consider a light but strong bicycle chain. The cyclist could be supplying a couple of hundred Watts of power to the wheels, pedalling once a second. The chain could be, say 0.5kg mass and any part of it would be traveling at say 0.1m/s over the sprocket. The total KE of the chain will be mv2/2=0.025J. So the KE of the chain represents 0.025/200 = 0.125% of the Energy supplied every second the wheels. The remaining 99.875% of the work is being transferred by the tension of the chain and its distance traveled (force times distance) and not the KE of the chain.Chan Pok Fung said:So the electrons only gain the energy very gently, but they accumulate energy throughout the journey in the wire.
sophiecentaur said:Here's an easy 'mechanical' argument that tells you the Kinetic Energy of electron motion is actually irrelevant. Consider a light but strong bicycle chain. The cyclist could be supplying a couple of hundred Watts of power to the wheels, pedalling once a second. The chain could be, say 0.5kg mass and any part of it would be traveling at say 0.1m/s over the sprocket. The total KE of the chain will be mv2/2=0.025J. So the KE of the chain represents 0.025/200 = 0.125% of the Energy supplied every second the wheels. The remaining 99.875% of the work is being transferred by the tension of the chain and its distance traveled (force times distance) and not the KE of the chain.
Bear in mind that the total mass of the 'mobile' electrons in a wire is 1/(1800X60) *of the mass of the positive copper ion cores and that they are drifting at a mm/s. What is transferring the Power along the wire is the fields 'pushing' the electrons along - the KE of the electrons is much much less of a proportion of the energy transferred than for the bicycle chain links.
*electron mass is about 1/1800 of the mass of a proton and the atomic mass of copper is about 60
Along with millions of other people. Glad it helped.Chan Pok Fung said:This is a good one, thanks! I have long been mistakenly understanding the power transmission mechanism of electricity.