Kirchhoff's Current Law

Steps:

• Recognize the statement describes balance of currents at a junction.
• Recall Kirchhoff's first law (KCL) states sum of currents entering a node equals sum leaving.
• Link KCL to conservation of charge, as charge can't accumulate at a point.
• Contrast with Kirchhoff's second law (KVL), which applies to voltage loops.

Why A is correct:

• Kirchhoff's first law (KCL) precisely states that the algebraic sum of currents at a node is zero, derived from charge conservation principle.

Why the others are wrong:

• B misidentifies it as second law (KVL) and ties to energy instead of charge.
• C correctly names first law but wrongly attributes to energy conservation.
• D names second law (KVL) but correctly ties to charge, which doesn't match.

Final answer: A