Using e in a Formula: Electric Potential

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In formulas involving electric potential, the charge of an electron is represented as -1.6x10^-19 C due to its negative charge. The work done by the electric force can be calculated using the potential difference between two points, with the formula Work = q(Va - Vc). This results in a consistent magnitude of work, regardless of whether the charge is treated as positive or negative. The key distinction lies in whether the work is considered done on the charge or by the charge. Understanding this concept is crucial for accurately calculating electric potential and work in physics.
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When using e (for electron) in a formula, do you use +1.6x10^-19 C or -1.6x10^-19 C?

For example:

http://i44.tinypic.com/25g9te8.jpg

An electron moved from c to a. How much work is done by the electric force?

Electric Potential
Point a = 6.2x10^5 V
Point c = -7.5x10^4 V

Work = (-1.6x10^-19 C) (Va - Vc) = -1.1x10^-13
-W(electric force) = +1.1 x 10^-13

OR

Work = (1.6x10^-19 C) (Va - Vc) = 1.1x10^-13
-W(electric force) = -1.1 x 10^-13
 
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Electron carries a negative charge.
 
According to the definition of the potential difference between the two points, it is the work done on the positive charge to move it against the electric force.
So the magnitude of the work is the same. Only difference is whether it is on the charge or by the charge.
 

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