Two tiny conducting spheres are identical and carry charges of -21.4 ÂµC and +46.5 ÂµC. They are separated by a distance of 2.39 cm. (a) What is the magnitude of the force that each sphere experiences, and is the force attractive or repulsive? (b) The spheres are brought into contact and then separated to a distance of 2.39 cm. Determine the magnitude of the force that each sphere now experiences, and state whether the force is attractive or repulsive. Solution here, q1 = - 21.4 * 10^-6 C q2 = 46.5 * 10^-6 C r1 = 2.39 cm = 0.0239 m a) as the charges are of opposite sign they will attract each other magnitude of force , F = K * q1 * q2 /r^2 F = 9 * 10^9 * 21.4 * 10^-6 * 46.5 * 10^-6 /0.0239^2 N F = 1.57 * 10^4 N b) when they are in contact the charges are on same potential as they are identical the charge on each , Q = ( Q1 + Q2)/2 Q = ( - 21.4 uC + 46.5 uC) /2 = 12.55 uC as they have the same charge the force is repulsive the magnitude of force , F = K * Q^2 /r^2 F = 9 * 10^9 * (12.55 * 10^-6)^2 /0.0239^2 N F = 2.5 * 10^3 N .