Kirchhoff's **voltage (loop) law** in any closed loop of an electrical network states:
A$\sum P = 0$
B$\sum IR + \sum \varepsilon = 0$
C$\sum I = 0$
D$V = IR$ only
Answer & Solution
Correct answer: B. $\sum IR + \sum \varepsilon = 0$
Around any closed loop, $\sum IR + \sum \varepsilon = 0$. This is **conservation of energy** — the net energy gained per unit charge in one full loop is zero.
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