How Do You Find the Electric Potential Energy of Three Point Charges?

In order to determine the electric potential energy of a three point charge, it is necessary to know two things: the individual charge on each point and the distance between the points. Using these quantities with Coulomb's constant will find the solution.

  1. Determine the distances in meters

    The distances between the charges must be expressed in meters for it to be in agreement with the units of the other quantities. Thus, if the distances given are in any other unit, convert them to meters before proceeding.

  2. Convert micro-coulomb to coulomb

    If the value of the charges are given in micro-coulombs, convert them to coulombs by multiplying the value by 1e-6. This is because Coulomb's constant is expressed in coulombs, and for it to cancel out to give joules, the units must be in agreement.

  3. Plug each value into the equation

    The equation to find the electrical potential energy between point charges is U = k(((q1 * q2) / r1_2) + ((q1 * q3) / r1_3) + ((q2 * q3) / r2_3)). K, Coulomb's constant, is equal to 8.99e9 (Nm^2 / C^2), r is the distances between point charges, and q is the charge in the point. Once all values are plugged in and calculated, the answer is given in joules.