What is the physical meaning of voltage variation in ac

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Discussion Overview

The discussion focuses on the physical processes occurring in conductors during alternating current (AC) flow, particularly the behavior of electrons and the interpretation of voltage variations, including negative voltage in a sine wave context.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant inquires about the behavior of electrons in a conductor when conducting AC and seeks to understand the physical meaning of negative voltage in a sine wave.
  • Another participant explains that AC voltage causes polarity to reverse in a smooth sine wave manner, comparing it to reversing a battery across a resistor, and notes that electrons flow from the more negative side to the more positive side.
  • A participant asks for validation of the statement that "voltage is more related to energy and current is related to number of electrons," seeking clarification on the relationship between voltage and current.
  • A later reply confirms the correctness of the statement regarding the relationship between voltage and energy, and current and the number of electrons.

Areas of Agreement / Disagreement

Participants express varying levels of understanding regarding the physical meaning of voltage and current, with some agreement on the relationship between voltage and energy, and current and electron flow, but no consensus on the broader implications of these concepts in the context of AC.

Contextual Notes

The discussion includes assumptions about the behavior of electrons and the interpretation of voltage that may not be universally accepted or fully explored, particularly regarding the nuances of AC behavior and the definitions of voltage and current.

Who May Find This Useful

Individuals interested in electrical engineering, physics, or those seeking to understand the fundamentals of alternating current and its effects on conductors may find this discussion relevant.

maheshwaran
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hey, i am trying to find what is the process going on in the conductor while conducting ac.
what is happening to electrons? what is the physical meaning of negative voltage in sin curve?
 
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Suppose you put a battery across a resistor. Whichever way you connect it, mark the resistor + and - according to the voltage polarity marked on the battery.

Now reverse the battery. The terminal marked + is now negative relative to the other terminal.

This is all that is happening with an AC voltage, but it happens in a smooth sinewave manner. If the AC input was slow enough, you could watch a voltmeter measuring it reverse polarity. It would read positive voltage for half the cycle and negative voltage for the other half of the cycle.

The electrons actually flow very slowly, so that the electrons that flow out of the resistor are not the ones that flowed into it, but the current effect happens very quickly, at speeds near the speed of light.

When you reverse the polarity of the supply, either with a battery or with an AC supply, the electrons flow in the opposite way to the way they were flowing before. They always flow from the more negative side of the supply to the more positive side.
 
thank you so much and please say whether the following statement is correct or not.
"voltage is more related to energy and current is related to number of electrons"
 
maheshwaran said:
thank you so much and please say whether the following statement is correct or not.
"voltage is more related to energy and current is related to number of electrons"

Yes.
 

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