1. The problem statement, all variables and given/known data So the Problem says . A 8V battery of internal resistance 0.5 Ω is being charged using another storage battery of 120 V using a resistance of 15.5 Ω calculate the Terminal Voltage of the battery . I really dont understand what is terminal voltage + how it changes It would be great if someone explained it . 2. Relevant equations V =IR For Batteries in series ε(total) = ε1 - ε2 (as positive is connected to the positive terminal) 3. The attempt at a solution Heres how I interpreted the circuit I did the solution and i got the right answer but I have no idea how it worked First I calculated the Equivalent ε = 120 - 8 = 112V also r equivalent = 15.5 Ω + 0.5 Ω = 16Ω So the Current flowing is 7 Amps Now what I did is Potenital Drop across the 120 V = potential drop across the 15.5Ω resistor + Terminal Voltage drop across the battery that gives Terminal Voltage = 11.5 V Which is correct now What I am not able to understand is what is Terminal Voltage and the way of calculating it and how it gets affected . Will there be terminal voltage change across 120 V battery too ? how ? also keeping the internal resistance of 8V battery in mind I can say that if 7A of current is flowing through it then the potential difference should be V = ε - I* internal resistance = 8 - 3.5 = 4.5V Why is this wrong ? How is it 11.5 V instead ?