1. a) Five short segments (labeled 1-5) of an insulating rod are arranged as shown. All...

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1. a) Five short segments (labeled 1-5) of an insulating rod are arranged as shown. All were rubbed with silk and have the same magnitude (positive) charge. A positively charged pith ball (akin to a test charge) is placed in turn at the locations marked by points A and B. Indicate the approximate direction of force on the pith ball at points A and B due to segment 5 alone. B 2 3 4 Top view What is the direction of the net force on the pith ball at point A? What is the direction of the net force at point B? Please explain how you determined your answer. b) In case A, shown at right, a point charge +q is a distances from the center of a small ball with charge +Q. In case B, the +q charge is a distance s from the center of a uniformly charged rod with a total charge +Q. Consider the following student dialogue: +9 Uniformly charged rod with total charge +Q +Q Case A Case B Student 1: "The charged rod and the charged ball have the same charge, +Q and are the same distance from the point charge, +q. So the force on +q will be the same in both cases." Student 2: "No, in case B there are charges spread all over the rod. The charge directly below the point charge will exert the same force on +q as the ball in case A. The rest of the charge on the rod will make the force in case B bigger." Neither student is correct. Discuss with your partners the errors made by each student. Write a correct description of how the forces compare in the space below. Explain. 1. a) Five short segments (labeled 1-5) of an insulating rod are arranged as shown. All were rubbed with silk and have the same magnitude (positive) charge. A positively charged pith ball (akin to a test charge) is placed in turn at the locations marked by points A and B. Indicate the approximate direction of force on the pith ball at points A and B due to segment 5 alone. B 2 3 4 Top view What is the direction of the net force on the pith ball at point A? What is the direction of the net force at point B? Please explain how you determined your answer. b) In case A, shown at right, a point charge +q is a distances from the center of a small ball with charge +Q. In case B, the +q charge is a distance s from the center of a uniformly charged rod with a total charge +Q. Consider the following student dialogue: +9 Uniformly charged rod with total charge +Q +Q Case A Case B Student 1: "The charged rod and the charged ball have the same charge, +Q and are the same distance from the point charge, +q. So the force on +q will be the same in both cases." Student 2: "No, in case B there are charges spread all over the rod. The charge directly below the point charge will exert the same force on +q as the ball in case A. The rest of the charge on the rod will make the force in case B bigger." Neither student is correct. Discuss with your partners the errors made by each student. Write a correct description of how the forces compare in the space below. Explain.