Kirchhoff's second law
Kirchhoff's voltage law (KVL) states that the sum of potential differences around a closed loop in a circuit is zero. Mathematically, Σ V = 0 around any closed path. This law is a consequence of energy conservation.
Formula
ΣV = 0 (around any closed loop)
Real World
Engineers designing the International Space Station's power distribution circuits use KVL to ensure voltage drops across each subsystem sum to zero, preventing power imbalances that could knock out life-support equipment.
Exam Focus
Always assign polarities before applying KVL; sign errors on EMF vs. voltage drop are the most common cause of lost marks.
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