See Attached .jpg for further information on this as well, please:
Three charges of equal magnitude q are fixed in position at the vertices of an
equilateral triangle (drawing). A fourth charge Q is free to move along the
positive x axis under the influence of the forces exerted by the three fixed
Find a value for s for which Q is in equilibrium. You will need to
solve a transcendental equation.
Electric fields of charges in equilibrium are studied. When another charge moves into the system, this affects the equilibrium. Therefore, the new equilibrium must be calculated. These calculations can be seen in the solution.