Parallel Combination - General Physics - Solved Past Paper, Exams of Physics

Download Parallel Combination - General Physics - Solved Past Paper and more Exams Physics in PDF only on Docsity! 1. (25 pts) a) (5 pts) How much energy does a 6 V battery give to 2 C of charge passing through it? ∆U = qV = (2)(6) = 12 J b) (5 pts) Why is the resistance of a parallel combination less than the individual resistances? Argue from a physical rather than mathematical standpoint. Since the current has the choice of more than one path, the total current is more than the current through either of the individual resistances. More current implies less resistance. c) (5 pts) If the chemical reaction in a battery always produces the same electric potential, why is the voltage at the terminals of the battery observed to decrease as the battery ages? As the battery ages, the internal resistance increases. This causes the charges to lose energy while they are still inside the battery. Thus their potential upon reaching the terminals of the battery is lower than the reaction potential. d) (5 pts) Is the electric field within a current-carrying conductor zero? Explain. No. If the electric field were zero, the charges would not accelerate and there would be no current! Keep in mind that this is no longer an electrostatic case. The charges do keep moving. e) (5 pts) We conventionally take current to be the flow of positive charge. What is actually going on in a real conductor? In a (metal) conductor, it is the (negative) electrons that are moving in the direction opposite to the conventional current.