A portable medical device is powered by a battery whose emf is constant but whose internal resistance is not negligible. While diagnosing a fault, a technician first operates the device with only a resistor R1 connected to the battery’s terminals. She then opens the circuit, inserts an additional resistor R2 in series with R1, and resumes operation.
Throughout the test the battery emf remains the same, and both resistors are ohmic.
(a) Qualitatively describe how the total external resistance connected to the battery changes when R2 is added. Explain your reasoning.
(b) Explain how the current supplied by the battery is affected by the addition of the series resistor.
(c) Discuss whether the terminal voltage of the battery increases, decreases, or remains unchanged after R2 is added, and justify your answer in terms of the battery’s internal resistance.
(d) Compare the electrical power delivered to R1 before and after R2 is added. Provide a clear chain of reasoning that supports your conclusion.