Definition
An electrical or electronic component that does not require an external source of power to perform its function and cannot amplify or generate a signal. Resistors, capacitors, inductors, and transformers are passive components.
Plain English
A part in an electrical circuit that just shapes or reacts to the current flowing through it. It doesn't add energy of its own and it doesn't make signals bigger.
Context Anchor
Seen in aircraft electrical and avionics discussions, especially when describing parts such as resistors, capacitors, coils, and transformers.
Derivation
Passive comes from the Latin passivus, meaning 'capable of being acted upon.' That fits here: a passive component reacts to the current passing through it rather than acting on it with added power.
Why Pilots Care
Understanding passive components helps a pilot follow basic electrical fault discussions and maintenance explanations without confusing a simple circuit part with a powered or signal-boosting device.
Analogy
A passive component is like a valve or spring in a water system: it can restrict, smooth, or store energy already moving through the system, but it does not pump more energy into the system.
Intuition Check
Passive does not mean the part is unimportant or doing nothing. Here it means the part does not add power or amplify a signal.
Example Sentence 1
The resistors and capacitors in the radio's filter circuit are passive components.
Example Sentence 2
Before testing the amplifier, the mechanic verified that all passive components were within tolerance.