An ideal battery creates a potential difference at the electrodes equal to its emf no matter what is attached. However, in reality, the electrochemical cells that creates the emf has its own internal resistance. In the circuit below the dashed box represents a real battery, and Rb is the internal resistance. It causes the battery output voltage (that you would measure between the top and bottom of the box) to be different from the emf. In this circuit, the emf is 9 V, the internal resistance is 2 Ω , R1 = 15 Ω , R2 = 10 Ω , and R3 = 20 Ω . a. What is the battery's output voltage in V with the switch open?
b. What is the battery's output voltage in V with the switch closed?