He's on the right track, and is 90% correct. Just one bit needs clarification.
He's talking about the propagation of potential and of current in a 2-wire waveguide. This is well covered in engineering E&M texts. He's talking about the propagation of electrical energy, not just current alone. Yes, energy flow in circuits includes volts and amperes both. When you connect up the battery in that second diagram, a wave of voltage moves along the parallel wires. A wave of current moves too. (and the wave of current goes outwards along BOTH wires. Weird, eh?) The "wave" is a classic EM wave, the same as radio and light waves. That's why it moves at the speed of light.
Note well that this wave propagation is very different than the net motion of electron-drift in those same conductors. Electron drift is the current, and current is a slow motion of charge carriers. His second diagram doesn't show current alone, it shows EM energy flow: it shows the watts. That energy flow goes at ~c, the speed of light.
Analogy: suppose a hillside is covered with gravel. Suppose you trigger a landslide by kicking some stones at the bottom. First some stones near your foot start moving. But this releases the stones higher up. And when those higher stones move, it releases still higher ones. A "wave" propagates rapidly upwards along the hillside. But the stones themselves, they move down.
In that avalanche, is the "wave" different from the "rock current?" Obviously it is. The gravel flow is slowly downwards. The "wave" might be incredibly fast, and it goes uphill.
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Does not the potential difference cause the wave to flow.
Current flows in both wires at the same time, not as a set of railway carriges going round in a circle.
Also electricity only flows at the speed of light when the Vf (velocity factor) is 1 (when Er is 1), ie in free air. As far as I can remember (today) the fastest wire for signal proporgation is a co-axial cable where it gets up to around 65-70%.
Current flows in both wires at the same time, not as a set of railway carriges going round in a circle.
Also electricity only flows at the speed of light when the Vf (velocity factor) is 1 (when Er is 1), ie in free air. As far as I can remember (today) the fastest wire for signal proporgation is a co-axial cable where it gets up to around 65-70%.
And I never said that either. You need to read exactly what I said. You said that electricity could not be a form of energy because it is conserved. I tried, but obviously failed, to point out that such conservation would be a requirement if electricity is a form of energy. That is, I am saying that your deduction is false: 'conserved implies "not energy"' is a false statement. I did not say, and would never say, that joules=coulombs. No physicist would. (BTW I am a real physicist)wbeatty said:
No, the bext textbooks are written by wise people such as Feynman. They know what is the appropriate level of detail and abstraction to suit the audience and the point they are trying to teach. You are confusing pedantry with accuracy.
I think this is the point where you go astray. By insisting that 'electricity' (a general term) must be equated to 'electric charge' (a specific term) you then force yourself to declare that a lot of other people, including professional physicists, don't know their own subject.
I once had a colleague who read a lot of stuff and knew quite a lot (in one sense). At an office party I once heard him explaining the theory of flight to an ex-colleague who had come back for the party. What I knew, and colleague did not know, was that ex-colleague had been an experienced pilot for many years, first as a hobby but more recently commercially. It was funny hearing someone who had never sat in a cockpit explaining flight to an airline pilot!
I would answer the questions with one word: energy. (You seem to have no issue calling them "electric companies.") If batteries lose it, then obviously your "it all goes out and comes back in" is a flawed statement. But we seem to agree it isn't "electricity" that's moving.
Were that true, physics would be much easier.
Volume concerns 3 dimensional space; length concerns 2 dimensional space. But I guarantee space was defined before if was quantified. Same with everything else that's ever been quantified.
That's odd, because I read the main point of the definition to be "charged particles of matter" ie charge. The M-W stuff is your straw man...
If electricity is charge, then this statement is incorrect, as it is indeed the charge in the battery that is being lost.
That's obvious equivocation - charge has a scientific and a colloquial meaning and you're conflating the two.
^ Quite a mysterious post I must say. Are you directing this at me? If so I fail to understand what you are trying to say. Are you saying it isn't the charge in the battery that is being lost?
First it was "electricity has a scientific and colloquial meaning", then it was "electricity is charge", now it's "charge has a scientific and colloquial meaning." Sadly humorous.
I figured I'd get called out for having gotten length wrong because it's only 1 dimensional.
First it was "electricity has a scientific and colloquial meaning", then it was "electricity is charge", now it's "charge has a scientific and colloquial meaning." Sadly humorous.
I figured I'd get called out for having gotten length wrong because it's only 1 dimensional.
In respect of batteries, "charge" has two quite different meanings. This is unfortunate, especially in the current 'debate'! Charge could mean electric charge e.g. the number of surplus electrons. For a battery this will always be almost zero, as electric charge leaving one terminal is balanced by electric charge entering the other terminal.
Charge can also mean potential for doing something useful. We talk about a battery being charged. A charged (in this sense) battery has exactly the same number of electrons as a discharged battery. The difference is chemical, not electrical. In essence, chemical potential energy has been stored typically by moving some constituent of the battery from one place to another (e.g. metal to a plate).
Charge can also mean potential for doing something useful. We talk about a battery being charged. A charged (in this sense) battery has exactly the same number of electrons as a discharged battery. The difference is chemical, not electrical. In essence, chemical potential energy has been stored typically by moving some constituent of the battery from one place to another (e.g. metal to a plate).
In a sense, it's not. If you count charges in the battery when fresh, then count them again when it's depleted, the number is the same. The state of the charges vis a vis their Gibbs free energy is different, however.
Here's a question we've talked about before- what has more mass, a charged capacitor or a discharged one?
Here's a question we've talked about before- what has more mass, a charged capacitor or a discharged one?
Any comments on the discussion about writing textbooks? Should an elementary book strictly avoid any 'untrue' statements, or is this impossible? My own view is that accuracy is important, but clarity may require some compromise. It helps, of course, if the writer is aware of when he is compromising so he needs to have a level of knowledge which exceeds the level of the book he is writing. Poor books can be written by people who don't realise when they are offering simplification or approximation, but people who are too advanced (or think they are) can also write bad books.
I once read of a physics teacher who reduced marks for pupils who wrote of light bouncing off mirrors, as in her view they should have said reflected. Unfortunately it may be that pupils who talk about bouncing have some understanding of what is happening (or at least the power of analogy) while the others may simply have learnt how to repeat a technical word. I'm glad my physics teacher wanted us to learn both the words and what they meant.
I once read of a physics teacher who reduced marks for pupils who wrote of light bouncing off mirrors, as in her view they should have said reflected. Unfortunately it may be that pupils who talk about bouncing have some understanding of what is happening (or at least the power of analogy) while the others may simply have learnt how to repeat a technical word. I'm glad my physics teacher wanted us to learn both the words and what they meant.
Oops, let's stop and clarify something.
Do you believe that a charged battery contains more electric charge, more Coulombs, than a discharged battery? If not, then please explain your statement above.
No. Only to a limited extent (like most PhD students in the UK, I was involved in undergraduate teaching by taking labs and tutorial groups. Years ago this was for physics students. More recently for EE students.)wbeaty said:
My claim to be a real physicist was in respect of education and published research, not teaching. My work covered quantum gravity, antiproton annihilation (both many years ago) and (more recently) dielectric measurement instrumentation. I also have EE papers.
Of course, who I am is irrelevant to the discussion so I probably should not have mentioned it. Truth is truth, whoever says it.
If you think I'm misusing the word "electricity," why not just give evidence? What's the big deal with that? Please, just cut/paste an example.
Read again carefully. I defined "electricity" as meaning "charge." I did so more than once. Then I used it very rigorously in exactly that way. I also described examples where people use it incorrectly. I also gave a list of many contradictory definitions, then directly below I stated that only No. 5 was the one accepted by science.
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