College Physics 10th Edition by Raymond Serway,Chris Vuille

Exercise 5

A battery with an internal resistance of 10.0 produces an open circuit voltage of 12.0 . A variable load resistance with a range from 0 to 30.0 is connected across the battery. ( Note: A battery has a resistance that depends on the condition of its chemicals and that increases as the battery ages. This internal resistance can be represented in a simple circuit diagram as a resistor in series with the battery.) (a) Graph the power dissipated in the load resistor as a function of the load resistance. (b) With your graph, demonstrate the following important theorem: The power delivered to a load is a maximum if the load resistance equals the internal resistance of the source.