Question

See the electrical circuit shown in this figure. Which of the following equations is a correct equation for it ?

• A. $\in_{1}-\left( i _{1}+ i _{2}\right) R + i _{1} r _{1}=0$
• B. $\epsilon_{1}-\left( i _{1}+ i _{2}\right) R - i _{1} r _{1}=0$
• C. $\epsilon_{2}- i _{1} r _{2}-\varepsilon_{1}- i _{1} r _{1}=0$
• D. $-\epsilon_{2}-\left( i _{1}+ i _{2}\right) R + i _{2} r _{2}=0$

Answer 1

Answer: (B)

Apply Kirchhoff's second law, aslo called loop rule.
The algebraic sum of the changes in potentail in complete transversal of a mesh (closed loop) is zero.
le, $\sum V=0$
Here, $\varepsilon_{1}=\left(i_{1}+i_{2}\right) R-i_{1} r_{1}=0$