Question

For a system of n charges, the total number of unique charge pairs whose potential energies must be summed is:

Options

• n(n-1)

• \[\frac{n(n-1)}{2}\]

• \[n^2\]

• \[\frac{n(n+1)}{2}\]

Answer 1

For n charges, the potential energy is summed over all unique pairs. The total number of such pairs is \[\frac{n(n-1)}{2}\], since each of the n charges pairs with (n-1) others and every pair is shared.