question_answer 11)

A storage battery of e.m.f. 8.0 V and internal resistance 0.5  is being charged by a 120 V dc supply using a series resistor of 15.5 . What is the terminal voltage of the battery during charging? What is the purpose of having a series resistor in the charging circuit?  

Answer:

During charging,                 V = E + I(r + R)                                                 Terminal Voltage,                  = 8 + 7 × 0.5 = 11.5 V.