According to this video https://www.youtube.com/watch?v=bHIhgxav9LY I have a question: If the glowing of a light bulb is the result of energy supplied from the electromagnetic field around a conductor, Why does the electricity not hurt me when I touch the cord from the turned on vacuum cleaner?
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$\begingroup$ Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking. $\endgroup$– Community BotNov 26, 2021 at 16:47
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1$\begingroup$ The light bulb (and the wire connected to it) is a good conductor, you're not - how are the two situations supposed to be comparable? See also physics.meta.stackexchange.com/q/13917/50583 for an overview of already extant questions about this veritasium video - perhaps one of them already clears up your confusion here. $\endgroup$– ACuriousMind ♦Nov 26, 2021 at 16:47
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2$\begingroup$ Also, to make questions more accessible and guard against link rot, please include at least author and title of resources you link in your question so the content can be reconstructed if the link rots away. $\endgroup$– ACuriousMind ♦Nov 26, 2021 at 16:48
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2 Answers
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The intuitive understanding of electric current as similar to water flow is very persuasive, and hard to quit. In spite of the efforts of the video makers, it is tempting to view the energy flow as a kind of a material flow. In this case we could be hurt by the fields if we are in the way.
But what the Pointyng vector only shows is that the battery is a source of electrical energy (from chemical reaction). The lamp is a sink of electrical energy (transformed in heat and light). But it is required a conductor wire connecting this components to get this energy flow.
If something touches the wire, and the striking example is a bird in a high voltage transmission line, the electric energy is negligible through its body.
answered Nov 26, 2021 at 23:37
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Your hand is a conductor, surrounded by insulating stuff, for that reason electric field is zero inside your hand, so also Poynting-vectors are zero inside your hand, so there is no energy flow inside your hand.
As there is an energy flow to the upstream and to the downstream of your hand, the flowing energy must make some turns when flowing around your hand. I mean when you are grabbing the cord.
(Maybe if you moved the hand to the downstream direction, you could steal some energy from the wire? From the space around the wire, I mean. :) )
For the sake of completeness, let's say your hand is an insulator, then same amount of Poynting-vectors are pointing into your hand from the upstream direction as are pointing out of your hand into the downstream direction, so your hand is nor absorbing any of the energy flowing through your hand, so it can not feel any effect of the energy.
