Charge 1 is located along the x axis and has a magnitude of +1.6E-6C and Charge 2 is located 1m away from charge 1 with a magnitude of -4.8E-6C. A third point charge of magnitude Q is brought from far apart and placed on the line joining the two charges and at a point where the charge q experiences no net force at all. What is the distance of that point from the origin and what should be the sign of this unknown charge q? This is what I came up with so far... F1 = K (Q1)(Q2)/X^2 F2 = K (Q2)(Q3)/(1m-x)^2 You set them equal to eachother and get K(Q1)(Q2)/X^2 = K(Q2)(Q3)/(1.00-x)^2 Cancel out K and Q3 leaving; (1.00-x^2)/X^2 = (Q2)/(Q1) 1.00-x/x = square root (4.8E-6C/1.6E-6C) 1.00-1x = 1.73x 1.00=1.73x +1x 1.00=2.73x x = .366 Does anybody know if this is correct? Also I do not know how to figure out what the sign of this charge should be so if anybody could help me I would appreciate it!