Definition
A voltage induced in a coil or winding that opposes the applied voltage causing the current. Back voltage is produced whenever current through an inductor changes, and its polarity acts to resist that change.
Plain English
When electricity flows through a coil and the flow tries to change, the coil pushes back with its own voltage in the opposite direction. This pushback is called back voltage.
Context Anchor
Seen in aircraft electrical system study, especially with starter motors, generators, relays, and other parts that use coils of wire.
Derivation
Back' here means 'opposing' or 'pushing the other way,' not 'rearward.' The term describes a voltage that acts back against the source that created it.
Why Pilots Care
Recognizing back voltage prevents misdiagnosis of charging system faults and helps avoid damage to aircraft electrical components.
Grounding Statement
When a motor starts turning, it can generate its own opposing voltage, so the current through the motor changes as the motor speeds up.
Intuition Check
Back voltage does not mean voltage located at the back of the aircraft or a battery wired backward. It means voltage created in a circuit that opposes the voltage being applied.
Example Sentence 1
When the landing gear solenoid was de-energized, the back voltage produced a spike that the suppression diode safely absorbed.
Example Sentence 2
Excessive back voltage in the magneto circuit can reduce spark strength if the capacitor is failing.