Electric Field and Force between two plates [general question]

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Discussion Overview

The discussion revolves around the calculation of electric fields and forces exerted on charges between two charged plates, specifically considering scenarios where one plate is earthed. Participants explore the implications of potential difference in these configurations.

Discussion Character

  • Exploratory
  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • One participant questions whether there is a difference in calculating the electric field or force when both plates are charged versus when one plate is earthed.
  • Another participant asserts that the calculation depends solely on the potential difference, suggesting that a +6V and -6V configuration is equivalent to a +12V and earthed configuration.
  • A participant reiterates that the potential difference remains 6 volts when the positive plate is at 6V and the negative plate is earthed at 0V.
  • There is a discussion about using the formula "F=e V/d" for calculating the force on a charge, with a focus on whether to use the value of V as 6 volts.
  • Another participant clarifies that if the potential difference between the plates is 6V, then it should be used as such in the formula, while also discussing the distinction between potential and potential difference in relation to Earth.

Areas of Agreement / Disagreement

Participants express differing views on the implications of earthed plates and potential difference, with no consensus reached on whether the configurations yield different results in calculations.

Contextual Notes

Some assumptions about the influence of nearby structures on the electric field are not fully explored. The discussion also highlights the relative nature of potential in relation to Earth, which may affect interpretations of the results.

Samurai44
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Greetings, I am just confused in something , Is there a difference when calculating the electric field , or a force exerted on a charge between two plates , if the two plates were :
a) both plates are charged ( connected to a power source) ,
OR
b) both plates are charged ( connected to a power source), but the negative plate is earthed , i.e 0 V at the negative plate .
 
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It only depends upon the Potential Difference (as long as there is no other structure nearby). SO connecting between +6V and -6V will give the same result as +12V and earth.
 
sophiecentaur said:
It only depends upon the Potential Difference (as long as there is no other structure nearby). SO connecting between +6V and -6V will give the same result as +12V and earth.
i mean let's suppose the voltage is 6V at the + plate , but the negative plate is 0v because its earthed
 
Samurai44 said:
i mean let's suppose the voltage is 6V at the + plate , but the negative plate is 0v because its earthed
In that case the potential difference will be 6 volts.
 
Doc Al said:
In that case the potential difference will be 6 volts.

so when finding a force on a charge(e .g an electron) between the plates , for example at the mid , using this formula "F=e V/d" ,, do we use the value of V as 6 ?
 
Samurai44 said:
so when finding a force on a charge(e .g an electron) between the plates , for example at the mid , using this formula "F=e V/d" ,, do we use the value of V as 6 ?
Field is Volts per Metre. If you have 6V PD between the plates then it's 6V for the formula.
I am just wondering if you could be worrying about the distinction between Potential and Potential Difference. When dealing with situations on Earth then you take Earth Potential as Zero and 'Potential' is relative to Earth. If the minus terminal of the supply is connected to Earth , the 'Potential' of the + terminal is 6V - and vice versa, when connecting the other way round.
 

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