I have read about this: Essentially in an insulators there is a big energy gap between the (valence) and the conduction band which is why there aren't many free electrons in a insulator. How does this relate to an insulator not being able to transfer electricity? Can't you just plug a battery into the insulator thus creating free electrons?
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$\begingroup$ Related question by OP $\endgroup$– BioPhysicistCommented Sep 21, 2020 at 22:00
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$\begingroup$ The article states: At the anode (which is a part of the battery) , the electrode reacts with the electrolyte in a reaction that produces electrons. These electrons accumulate at the anode. $\endgroup$– Faheem AzeemiCommented Sep 21, 2020 at 23:27
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$\begingroup$ Just adding electrons to an insulator is how things give you a static shock. The extra electrons are there but still can't flow easily through the material and are basically of stuck at the location you put them onto the insulator. It's easier for them to flow off the area where they reside into you at the location you are in contact with than it is for them to flow to somewhere else on the insulator. $\endgroup$– DKNguyenCommented Sep 22, 2020 at 3:32
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2 Answers
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Can't you just plug a battery into the insulator thus creating free electrons?
Batteries don't "create" free electrons. Batteries give (potential) energy to free electrons in insulators and conductors by producing an electric field that forces the free electrons a to move (create a current).
However, I have learned that the battery extracts electrons through a chemical reaction and then sends it through the wire. Here is a website explaining this. science.org.au/curious/technology-future/batteries
I'm not sure which part of the link gives you that impression so you need to tell us which specific statement in the link gives you that impression. The chemical reactions enable the battery to supply energy to the electrons entering the battery from the circuit so that they can exit the battery with more energy in order to do work in moving through the circuit.
Here is a part of the article that states this: "At the anode (which is a part of the battery) , the electrode reacts with the electrolyte in a reaction that produces electrons. These electrons accumulate at the anode." Then the article goes further in explaining how the positive terminal of the battery 'attracts' the electrons that are in the negative terminal of the battery. –
The accumulation of electrons at the anode (and removal of electrons at the cathode) produces an electric field. That electric field provides the force needed to do work to move the free electrons in the circuit. So the battery provide energy to move free electrons in the circuit, but it doesn't add electrons to the circuit.
Hope this helps.
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$\begingroup$ However, I have learned that the battery extracts electrons through a chemical reaction and then sends it through the wire. Here is a website explaining this. science.org.au/curious/technology-future/batteries $\endgroup$ Commented Sep 21, 2020 at 21:45
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$\begingroup$ @FaheemAzeemi I've updated my answer to respond to your follow up comment. Hope it helps. $\endgroup$– Bob DCommented Sep 21, 2020 at 22:03
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$\begingroup$ Here is a part of the article that states this: "At the anode (which is a part of the battery) , the electrode reacts with the electrolyte in a reaction that produces electrons. These electrons accumulate at the anode." Then the article goes further in explaining how the positive terminal of the battery 'attracts' the electrons that are in the negative terminal of the battery. $\endgroup$ Commented Sep 21, 2020 at 23:33
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$\begingroup$ @FaheemAzeemi See new (and final) update to my answer. If it doesn't satisfactorily answer your question, sorry. $\endgroup$– Bob DCommented Sep 21, 2020 at 23:48
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The free electrons of a conductor are not so free. They occuppy quantum states, each of them with a given momentum and energy. The difference of energy between the states is very low, and the set of them is called a band. All the lower energy states are occupied. That means electrons going to all directions, so that the net current is zero.
When an electric field is applied, if there are available states just above the high energy electron, the energy and momentum distribution changes, and there is more electrons with momentum in one direction than the opposite leading to a net current.
In an isolator, there are no available quantum states in the band, all of them are occupied. So, the distribution of momentum doesn't change with the applied field. There is no net current.
answered Sep 22, 2020 at 0:24