Chapter 5.1, Problem 2bT

Two more $+Q$ charges are held in place the same distance s away from the $+q$ charge as shown. Consider the following student dialogue concerning the net force on the $+q$ charge:

Student 1: “The net electric force on the $+q$ charge is now three times as large as before, since there are now three positive charges exerting forces on it.”

Student 2: “I don’t think so. The force from the $+Q$ charge on the left will cancel the force from the $+Q$ charge on the right. The net electric force will be the same as in part A.”

1. Do you agree with either student? Explain.
2. Indicate the direction of the net electric force on the $+q$ charge. Explain.
3. What, if anything, can be said about how the magnitude of the net electric force on the $+q$ charges changes when the two $+Q$ charges are added? Explain.