Earth Potential

Replies

• 

  Kaustubh Katdare

  Refer to these threads: What is Earth Potential? & How can ground provide return path?
  
  Let us know if you got the answer.
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  pinank

  the links are reference to ground resistance....my question that if current is flowing through earth (via some return path) then there should be some potential difference in Earth meaning potential at Mumbai may be different than in Delhi..But thats not true...y?
• 

  Kaustubh Katdare

  Okay, good. As you're aware, ground is any large surface. Also, potential is a value with 'reference' to this large surface. This large surface would be 'considered' as 'Zero' potential for the reference sake, so that the potential of the other points would be calculated with reference to it.
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  Jeffrey Arulraj

  Potential is relative and not absolute
  
  We use the potential of the earth surface as an reference and it is ideally assumed as 0 V
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  Sindhu Chowdary

  electrical potential is measured as V = kQ / R .. ..(J/C or V)
  Since the net charge possessed by the Earth is zero it's surface potential s zero.
  
  Uncharged objects do not create surrounding electric fields in which separated charges might possess electrical PE ... so it is quite logical to use the earth connection as a reference zero for the energy state of electrons in circuit work. It's enormous size and good conductivity means that 'local' transfers of charge to or from Earth will not make any significant difference to it's surface potential.
• 

  lal

  gwendollen

  electrical potential is measured as V = kQ / R .. ..(J/C or V)
  Since the net charge possessed by the Earth is zero it's surface potential s zero.
  
  Uncharged objects do not create surrounding electric fields in which separated charges might possess electrical PE ... so it is quite logical to use the earth connection as a reference zero for the energy state of electrons in circuit work. It's enormous size and good conductivity means that 'local' transfers of charge to or from Earth will not make any significant difference to it's surface potential.

  That is true based on the assumption/convention that "net charge possessed by earth is zero" in electrostatics.
  
  By Ohm's law, when current flows through a conductor a potential difference is developed across it and that happens over the surface of earth too! There is a phenomenon called "earth potential rise" where the potential at a point on the earth's surface rises when large amount of current flows through that point (mostly due to faults). Potential decreases as the distance from that point on the earth's surface increases. Earth potential rise is a matter of concern when designing substations and generating stations. But this potential rise, which may be large enough to be hazardous, doesn't extend to a large area or distance from the point of earthing. It is confined to a very very small area which is a negligible fraction of the total surface area of earth. So it is definitely valid to consider the earth's potential as zero anywhere over its surface!
• 

  Sindhu Chowdary

  lal

  That is true based on the assumption/convention that "net charge possessed by earth is zero" in electrostatics.
  
  By Ohm's law, when current flows through a conductor a potential difference is developed across it and that happens over the surface of earth too! There is a phenomenon called "earth potential rise" where the potential at a point on the earth's surface rises when large amount of current flows through that point (mostly due to faults). Potential decreases as the distance from that point on the earth's surface increases. Earth potential rise is a matter of concern when designing substations and generating stations. But this potential rise, which may be large enough to be hazardous, doesn't extend to a large area or distance from the point of earthing. It is confined to a very very small area which is a negligible fraction of the total surface area of earth. So it is definitely valid to consider the earth's potential as zero anywhere over its surface!

  it means simply because the surface of the earth is too large,there will be no effect of charge and so the pd of earth can be considered as zero..can we think like this?
• 

  lal

  Yeah! Since the earth's surface is too large, a rise in potential at one negligibly small area (compared to the total area) on some place over the earth doesn't make a difference. So we can safely consider the earth's potential as zero.
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  vamsi kancharla

  pinank

  We say that the potential of earth is considered zero?
  
  Why is it that potential at all points on earth is zero? Earth has resistance and there is fault current flowing through it.. so the potential needs to be there...please answer😛

  since the surface of the earth is very large ,the current distributes to the ground since large area 0 potential to the ground