Comments by "George Reynolds" (@karhukivi) on "The Engineering Mindset" channel.

  1. Doesn't make any difference! They didn't know the polarity of electrons for a long time after electricity was discovered. Electron flow is only relevant in electrochemistry and physics e.g. gas discharge devices etc., not for automotive or industrial electricians.
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  2.  @augustaking8  Who exactly is lying and why? "Conventional" flow is just a convention before they understood electrons. I did say electron flow is only relevant in physics and electrochemistry, it doesn't matter a whit to a guy servicing an amplifier or wiring a house and certainly not to an automotive electrician fitting a voltage regulator to an alternator, which is, incidentally, the subject of the video you were watching!
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  3.  @augustaking8  This is a video to explain to people with no electrical knowledge at all what an alternator is. The animations for electrical devices are always simplified.
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  4.  @augustaking8  In some schools and universities electron flow is the teaching base. However, conventional symbols for electronic components have been devised with arrow-like shapes to indicate conventional flow, e.g. diodes, transistors etc. Electrochemistry requires electron flow knowledge as the electrode reactions only make sense in this domain. Physics students understand both conventions but beginners at electricity struggle with basic concepts such as magnetism and three-phase, even current and voltage, ac and dc. You can see this in the comments on other videos, so best to keep it simple until they understand the basic idea and then later introduce the more complex elements. A pity Benjamin Franklin called it wrongly back in 1752, 145 years before the electron was discovered to be the charge carrier!
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  5. Then perhaps you should stop paying the electricity company and rip out all the wires!
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  6. Electrostatic charge can be transferred through them, so a transient current does pass, but not a sustained one unless it is alternating current.
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  7.  @PlayitonPan  They don't short circuit as the voltage on the neighbour is opposing it, but they do equilibrate and they will usually end up with exactly the same voltage.
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  8. Most electronic technicians have used conventional current all their lives with absolutely no problem. Electron current, on the other hand, creates much confusion with a counter-intuitive flow from negative to positive giving some people real difficulties!
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  9.  @augustaking8  You should ask the students doing electricity and electronics that have such difficulty with that. You're clearly not in the teaching profession!
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  10.  @augustaking8  You make this sound like religion!
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  11.  @Total-Solutions  A 100 Ohm resistor will not test a car battery, nor will it draw 700A. By Ohm's law the current I = V/R = 12/100 = 120mA.
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  12. Because the ground may not be very conductive everywhere. The bar could be in dry gravel while a copper pipe might be in contact with wet soil, so bonding them together prevents a difference in potential between them.
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  13.  @franciscoperna7963  It's the current you have to start with. A simple LED (not in some device with other components) will tolerate 10 to 30 mA, (0.01-0.03A) so you must choose a resistor to put in series with the LED that will limit the current. If you want to connect it to a 12V supply, then 12/0.02 = 600 Ohms, so you could use a higher resistor value of 680 Ohm resistor and the current would not exceed 20 mA. There is a small voltage drop across a LED (depending on its colour ; 1.8V for red to 3.3V for blue) so a more exact calculation would be for a blue LED of (12-3.3) 8.7/0.02 = 435 Ohms and nearest resistor value of 470 Ohms for the series resistor. If the LED is not bright enough, you can reduce this resistance to a lower value but if it is too bright, then you risk burning it out. Trial and error is the last resort, I have burnt out many LEDs from experimenting! Hope this helps.
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  14. Three things could happen - they won't light up, they light up, or one blows. The circuit should be designed for them to light up at a suitable brightness, i.e. the ideal current..
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  15.  @Willy_Tepes  That's correct, to get the ideal current in each LED. Some LEDs have resistors built-in and others are even more clever with current regulation etc. But for plain vanilla LEDs you aim to get the ideal current as per the specs.
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  16. if you look at most of the questions, the understanding of what cells and batteries do is rather limited, so semantics are not really an issue here!
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  17.  @VictorGonzalez-mi5kd  The battery helps to stabilise the voltage at around 12V. If you remove the battery with the engine running the voltage will increase to 14.4V or even higher and this will help burn out the lights and other devices sooner than they should. I burnt out my radio because of a higher than normal charging voltage.
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  18. You will be on a delicate edge. A shade less voltage and the LED goes out, a shade more and it pops! Not a good strategy....
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  19. If it is charging at more than 14.4 V then there is a voltage regulator problem and other electric/electronic devices could be damaged, e.g. radios satnavs, headlights etc.
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  20. They will have twice the voltage and so they can supply twice the current through the same resistor, but the total capacity remains the same.
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  21. Incorrect. The speed of the vehicle (not the acceleration) is proportional to the crankshaft speed via the gearing.
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  22. No! The internal resistance rises as a battery loses its charge (due to the chemicals being used up, mainly the zinc case) so on open circuit (i.e. no load connected) a dead battery might show the full nominal voltage with a high-impedance voltmeter.
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  23. "Phase" is the jargon for "hot" or "live" wire. "Hot" can also refer to temperature and "ive" can also refer to something living. A device to test which wire is "live" is called a "phase tester". The other meaning of phase is more technical, and deals with the timing of the voltage oscillations in the different wires. The split phase just means that the live circuit has been divided into two wires or "phases". Every trade or profession uses some jargon to simplify conversation between colleagues, not always to be taken literally.
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  24. Same thing. A dying battery is simply losing its capacity due to sulphating of the electrodes.
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  25. It doesn't "know", there is a potential difference and the current will flow across it if it can.
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  26. No. The two batteries have to be connected to form a circuit.
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  27. And some have plastic in places where you don't see it. No guarantee that the "ground" is actually in contact with the earth!
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  28. Yes it is. Most people think "cells" are in prisons or perhaps something to do with cellular phone networks.
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  29. InpPhysics you use electron flow for gases and also for electrochemistry. However for practical electronic design of circuits it makes no difference whatsoever and as the symbols for diodes and transistors have the arrows by convention, and most people can relate to positive "flowing" to negative, it seems slightly more intuitive. We can blame Benjamin Franklin for calling it wrong 150 years before the electron was discovered!
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