Each part of Figure Q218 shows one or more point charges The

Each part of Figure Q21.8 shows one or more point charges. The charges have equal magnitudes. If a positive charge is moved from position i to position f, does the electric potential energy increase, decrease, or stay the same? Explain.

Solution

A) increases and then decreases

Because potential energy is inversely proportional to distance between charges. So it increases as it moves from i towards positive charge and then decreases as it moves from positive charge towards f.

B) decreases

Because distance increases between charges as moving from i to f

C) decreases and then increases

Because there is negative charge. Also distance first decreases and then increases

D) decreases

Because distance increases while moving from i to f