Question

The emf of a storage battery is 90 V before charging and 100 V after charging by a direct current voltage supply. When charging began the current was 10 A. What is the current at the end of charging if the internal resistance of the storage battery during the whole process of charging may be taken as constant and equal to 2 ohms?

• A. 5 A
• B. 10 A
• C. 15 A
• D. 20 A

Answer 1

The correct option is A

5 A

Initital current, $I_i=\frac{E_o-E_i}{r}\Rightarrow 10=\frac{E_o-90}{2}\Rightarrow E_o=110V$
Now, $I_f=\frac{E_o-E_f}{r}=\frac{110-100}{2}=5A$