A 6.0 V battery has an internal resistance r. The measured voltage (emf of the battery) is 6.0 V. When connected to a resistor R the terminal voltage is 5.9 V and the current is 0.18 A. I managed to get a) What is the internal resistance r of the battery? 0.556 ohm as well as b) What is the value of the external resistor R? 32.78 ohm but i cant figure out what to do when they ask me c) What is the energy dissipated inside the battery in 4.4 minutes? and d)When a second identical battery is added in series and the external resistor is R = 29 Ohms what is the resulting current? Please help me. I have been trying this for an hour!