Electricity Basics: Voltage 220V & Potential Difference

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Discussion Overview

The discussion revolves around the concept of voltage, specifically the meaning of 220V in the context of Indian standard electric supply at homes. Participants explore the relationship between voltage and potential difference, as well as the implications of alternating current versus direct current.

Discussion Character

  • Conceptual clarification
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant asks about the physical meaning of 220V and whether it represents the potential difference between the power station and home wiring.
  • Another participant confirms that 220V is indeed a potential difference and explains that voltage is typically referenced to ground, which is considered zero potential.
  • A different viewpoint notes that the potential difference between the two wires in the home supply is a sine wave, with 220V being the root-mean-square (rms) value, which reflects the average work done by current flow.
  • Some participants highlight that the definition of voltage as potential difference is strictly applicable to direct current (DC), while the context of the discussion involves alternating current (AC).

Areas of Agreement / Disagreement

Participants generally agree that 220V represents a potential difference, but there is some contention regarding the application of this concept to alternating current versus direct current. The discussion remains unresolved regarding the nuances of these definitions.

Contextual Notes

There are limitations in the discussion regarding the assumptions made about the reference potential and the nature of the current being discussed (AC vs. DC), which may affect the interpretation of voltage and potential difference.

Physics Newbie
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In Indian standard electric supply at homes is of 220V and 50Hz, What is the physical meaning of Voltage 220V? Does Voltage means Potential difference? I know that potential difference(pd) between two points is the work-done per unit charge to move it between the two points. Is 220V the pd between the power station nearby and my home wiring to the appliance?
Confused :(
 
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Yes, it is potential difference. In electronics, we usually call this quantity as voltage. When we say voltage, for example, 5 V, it is the potential difference between two point. Normally when electronics is powered from power line, not battery, ground (connection to earth, I mean surface of the soil in this planet. The soil of this planet is considered as infinity reservoir of charge) is reference potential as zero. All most devices has ground connection for voltage (potential) reference.

220 V is voltage difference between two wires of powerline (one is for forward current to device and other is for its returning.) The return path is eventually connected to Earth thus we treat this line as 0 voltage when low frequency and low current are used.

Output of power stand has very big voltage and this voltage is down-converted to 220 V in house via transformer.
 
Physics Newbie said:
In Indian standard electric supply at homes is of 220V and 50Hz, What is the physical meaning of Voltage 220V? Does Voltage means Potential difference? I know that potential difference(pd) between two points is the work-done per unit charge to move it between the two points. Is 220V the pd between the power station nearby and my home wiring to the appliance?
Confused :(

You have two wires into your house. If you were to measure the potential difference between them as function of time, you would see that it is a sine wave with a frequency of 50 cycles per second and a peak-to-peak amplitude of about 340 volts. 220V is what you get when you calculate the root-mean-square (google for "rms voltage") average of the potential difference between the wires over time, and is the best measure of the amount of work that will be done by a given current flow.
 
goodphy said:
Yes, it is potential difference. In electronics, we usually call this quantity as voltage. When we say voltage, for example, 5 V, it is the potential difference between two point.

Note that this is only strictly true for direct current (DC), whereas the line voltage that OP is asking about is alternating current.
 

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