A long non-conducting, massless rod of length L pivoted at its centre and balanced with a weight w at a distance x from the left end. At the left and right ends of the rod are attached small conducting spheres with positive charges q and 2q respectively. A distance h directly beneath each of these spheres is a fixed sphere with positive charge Q.
Note Ignore the force between Q (beneath q) and 2q and the force between Q (beneath 2q) and q. Also the force between Q and Q.
a. Find the distance x where the rod is horizontal and balanced.
b. What value should h have so that the rod exerts no vertical force on the bearing when the rod is horizontal and balanced?