question_answer

A battery of 20 cells (each having e. m. f. 1.8 volt and internal resistance 0.1 ohm) is charged by 220 volts and the charging current is 15A. The resistance to be put in the circuit is

A)  10.27 ohms        

B)         12.27 ohms

C)  8.62 ohms       

D)         16.24 ohms

Correct Answer: A

Solution :

                                  \[V=iR\]                   \[220-36=15R\] \[\Rightarrow \]                              \[R=\frac{184}{15}\]                                    \[=12.27\Omega \] \[\therefore \]             \[{{R}_{1}}=12.27-2\]                                   \[=10.27\Omega \]