Solve Electrical Work Problem: 15V to 5V

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    Electrical Work
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Discussion Overview

The discussion revolves around a homework problem involving the calculation of electrical work done when the voltage of a hypothetical electrochemical cell drops from 15 V to 5 V. Participants are attempting to resolve discrepancies in their calculations and clarify the parameters of the problem.

Discussion Character

  • Homework-related, Technical explanation, Debate/contested

Main Points Raised

  • One participant presents a calculation for the work done, yielding a result of -6.954 * 10^-11 J, but notes a discrepancy with a friend's answer of 1.4 *10^-7.
  • The participant outlines their approach using the equation for electrical work, incorporating variables such as electric potential and permittivity.
  • Another participant questions the specifics of the system being analyzed, seeking clarification on what is meant by "system."
  • A further inquiry is made regarding the geometry of the system, as the edge length of 1 cm could apply to various configurations.

Areas of Agreement / Disagreement

Participants have not reached a consensus on the correct answer or the interpretation of the problem. Multiple viewpoints regarding the system's definition and geometry remain unresolved.

Contextual Notes

The discussion lacks clarity on certain assumptions, such as the specific configuration of the electrochemical cell and how the edge length relates to the calculations. Additionally, there are unresolved mathematical steps in the calculations presented.

punjabi_monster
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Hi there. I was attempting this problem but my answer is not agreeing with my friends.
He got 1.4 *10^-7
Any help will be appreciated.

Homework Statement


Calculate the work done on a system if its voltage drops from 15 V to 5 V.
edge length= 1 cm
water permittivity e=78.54e


Homework Equations



dwelec = (elec pot.)dQ
Q=(elec pot)2ed
e=78.54 * eo

The Attempt at a Solution


w = (elec pot.)f (Qf - Qi)
=(elec pot.)f (2ed)[(elec pot.)f - (elec pot.)i]
=(5V)(2(78.54)(8.854*10^-12)(0.001)(5V-15V)
= -6.954 * 10^-11 J
 
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What is the system in question?
 
its an hypothetical electrochemical cell.
 
Geometry? Edge length of 1 cm can be appliead to anything.
 

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