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A student writes the junction rule as "the algebraic sum of currents at a node is zero." This statement is equivalent to Kirchhoff's Current Law provided that
Aall currents are treated as positive regardless of direction
Bcurrents entering are taken with one sign and currents leaving with the opposite sign
Conly outgoing currents are included in the sum
Donly one branch current is unknown
Answer & Solution
Correct answer: B. currents entering are taken with one sign and currents leaving with the opposite sign
The form "algebraic sum of currents is zero" works when a sign convention is used consistently. If entering currents are positive, leaving currents must be negative, or vice versa. Then KCL becomes equivalent to current in equals current out.