A storage battery of emf 8.0 V and internal resistance 0.5 Ω is being charged by a 120 V dc supply using a series resistor of 15.5 Ω. What is the terminal voltage of the battery during charging? What is the purpose of having a series resistor in the charging circuit?
E=8V, internal resistance R1=0.5Ω V=120V, resistance R2=15.5Ω Effective voltage V′=V−E=112 V I=R1+R2V′=7 A Voltage across R1=IR1=3.5 V Terminal voltage =8+3.5=11.5 V Series resistor in the charging circuit limits the current drawn from the external source.
