Definition
A voltage deliberately applied in opposition to another voltage so that the two partially or fully cancel each other. The net voltage seen by the circuit is the difference between the two, allowing precise control, measurement, or reduction of the original voltage.
Plain English
A voltage pointed the opposite way to another voltage, so the two push against each other and the result is smaller than either one alone.
Context Anchor
Seen in aircraft electrical system theory and troubleshooting, especially when checking why a circuit is receiving less voltage than expected.
Derivation
From the verb 'to buck,' meaning to push back against or resist (as a horse bucks a rider). The voltage is set up to push back against another voltage, so the name describes exactly what it does.
Why Pilots Care
Correct bucking voltage prevents over-voltage or under-voltage conditions that can damage avionics, discharge the battery, or cause instrument failures in flight.
Analogy
Think of two people pushing on opposite sides of a door. If one pushes a little harder, the door moves only by the difference. Bucking voltage works the same way -- the net voltage is just the difference between the two opposing pushes.
Intuition Check
“Bucking” does not mean the voltage is jumping around. Here it means the voltage is opposing another voltage and reducing the result.
Example Sentence 1
The voltage regulator uses a bucking voltage to oppose the generator output and hold the system at a steady 28 volts.
Example Sentence 2
During troubleshooting the technician measured insufficient bucking voltage and traced the fault to a failed regulator.