- I have been learning in my physics class that EMf is produced when there is electrostatic potential, that EMf is produced when current flows against the electric field, from the lower potential point (-ve terminal) to a higher potential point (+ve terminal). In nature, Current always travels from a higher potential to a lower potential. From where do charges get energy to travel from a lower to a higher potential point?
- Let's suppose that there is a battery. It has already produced EMF as it has lesser -ve charges at the positive terminal and more -ve charges at the -ve terminal. when the voltage is applied, the current travels from a higher to lower potential point, meaning from the +ve to the -ve terminal. What I don't understand here is why does +ve terminal have a higher potential point than the -ve terminal. Second, even though +ve terminal has a higher potential point, it has a less number of negative charges. Is there any difference in having more or less number of charges?
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$\begingroup$ Having some trouble following you. Let's start with this. When you refer to "current", are you referring to the flow of positive charge (conventional current) or negative charge (electrons)? $\endgroup$– Bob DCommented Apr 29, 2021 at 20:19
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$\begingroup$ My teacher tells me that in reality current travels conventionally $\endgroup$– AsadCommented Apr 29, 2021 at 20:25
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$\begingroup$ And what does your teacher mean by "conventionally". Does your teacher mean the flow of positive or negative charge? $\endgroup$– Bob DCommented Apr 29, 2021 at 20:34
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$\begingroup$ Ok that's kinda obvious, conventional flow of current simply means flow of negative charges from the positive to the negative terminal of the battery $\endgroup$– AsadCommented Apr 29, 2021 at 20:40
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$\begingroup$ Actually, that is not correct. Conventional current is defined as the flow of positive charge not electrons. In reality, current flow is negative charge (electrons) with some exceptions notably in semiconductors and current in plasmas. The definition of conventional current as flow of positive charge is historical (by Ben Franklin) before current was fully understood. Unfortunately we are stuck with it. When it comes to circuit analysis it doesn't matter as long as we're consistent. But at least now I understand your post and will attempt an answer. $\endgroup$– Bob DCommented Apr 29, 2021 at 21:55
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