Definition
A pair of fundamental rules governing electrical circuits. Kirchhoff's Current Law states that the sum of currents entering any junction in a circuit equals the sum of currents leaving it. Kirchhoff's Voltage Law states that the sum of voltage drops around any closed loop in a circuit equals the total voltage applied to that loop.
Plain English
Two rules that describe how electricity behaves in a circuit. First rule: whatever current flows into a point has to flow back out of it — none disappears. Second rule: if you trace a complete loop in a circuit, all the voltage gains and drops have to add up evenly.
Context Anchor
Seen in aircraft electrical system study and troubleshooting, especially when tracing voltage and current through a circuit.
Derivation
Named after Gustav Kirchhoff, a 19th-century German physicist who first described these rules in 1845. The laws still carry his name because they remain the foundation of circuit analysis.
Why Pilots Care
These laws are the basis for diagnosing electrical faults in aircraft. When a circuit isn't behaving as expected, technicians use these rules to track where current should be going and where voltage should be dropping, which leads them to the failed component.
Analogy
Think of water pipes. Whatever water flows into a junction must flow out — it can't pile up or vanish. And if you follow a loop of pipe back to where you started, the pressure changes along the way have to balance out to zero. Electricity follows the same logic.
Grounding Statement
If a technician checks an aircraft circuit, Kirchhoff’s Law gives a basic way to compare what the meter shows with what the circuit should be doing.
Intuition Check
Do not read “law” here as a regulation. In this term, it means a rule of how electricity behaves in a circuit.
Example Sentence 1
The technician applied Kirchhoff's Law to verify that the current measured at the junction matched the sum of the currents flowing through each branch.
Example Sentence 2
Applying Kirchhoff’s voltage law showed that the sum of voltage drops across the aircraft lighting circuit was zero.