4. Let q be a positive source charge and q be the test charge. When q is changed from positive to negative, what happens to the potential energy of the two-charge system? a. It increases. b. It decreases. c. It remains the same. d. None.
5. Two conducting wires A and B of the same length and radius are connected across the same potential difference. Conductor A has four times the resistivity of conductor B. What is the ratio of the power delivered to A to the power delivered to B? a. 2 b. V2 4 1/V2 1/2 none.