question_answer

In a given circuit, each cell has an emf of 0.15 V and internal resistance of 0.25 \[\Omega \]. Find the current in the circuit.

A)  0.12 A                  

B)  0.012 A

C)  0.045 A               

D)  0.45 A

Correct Answer: C

Solution :

                Number of cell \[(n)=3\] Number of row \[(m)=10\] Internal resistance \[=0.25\,\Omega \]                 \[R=10\,\Omega \]                 E = 0.15 V We know that,                 \[i=\frac{mnE}{nr+mR}\] \[\Rightarrow \]               \[i=\frac{10\times 3\times 0.15}{3\times 0.25+10\times 10}\] \[\Rightarrow \]               \[i=\frac{4.5}{0.75+100}\] \[\Rightarrow \]               \[i=\frac{4.5}{100.75}\] \[\Rightarrow \]               \[i=0.0446\] \[\Rightarrow \]               \[i=0.045\,A\]