Electric Potential

Many students still think of work as only being found from F dot distance. This view ,while largely correct is not particularly useful when F varies over the distance, especially when this variation is not linear the way it is with a spring ( here F = k delta x so even though k varies it is easy to calculate the work). The best way to approach work with a non constant force is to remember that work changes energy. For example, if you are moving a charge QT without large changes in KE the work = delta PE = QT x delta V.

Some students are still using the potential created by a test charge in calculating the potential the test charge feels. Don't do this, see earlier post on subject.