-12.42 Joules of work are required to move a charge of -.1602 C from point A to point B. What is the potential difference in Volts from A to B?
A Volt is a measure of work per unit charge, measured in Joules per Coulomb. When a field does -12.42 Joules of work on -.1602 Coulombs of charge, the potential difference is (-12.42 J)/(-.1602 C) = 77.52 J/C = 77.52 Volts.
If a charge Q (measured in Coulombs) moves from one point to another, requiring work `dW (in volts, or Joules / Coulomb), then the potential difference between the points is `dV = `dW / Q (the number of Joules divided by the number of Coulombs).
The figure below shows a charge Q moving from a low potential V1 to a high potential V2. The potential difference is `dV = V2 - V1, and the work required to move the charge is W = Q `dV (`dV is measured in Joules of work required per Coulomb of charge, so work must be the product of Q (Coulombs) and `dV (Joules / Coulomb) ).
It follows that `dV (the number of Joules/Coulomb) is obtained by dividing `dW (the work in Joules) by `Q (the charge in Coulombs).
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