In this video students were asked to solve for the potential in all space due to a ring of charge Q and radius R. This activity is described in Electric Potential Activity .

One student is starting with kQ / |r - r'| and trying to turn this into an integral that has charge density. Another student uses the drawing and gestures along with words to show that the charge density is Q/(2(pi)R) and that when integration from 0 to 2pi all the charge will be summed up.

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