Definition
The ability of a component or material to store an electrical charge. It is measured in farads and depends on the surface area of the conducting plates, the distance between them, and the type of insulating material separating them.
Plain English
How much electrical charge something can hold. A part with high capacitance can store more charge; a part with low capacitance stores less.
Context Anchor
Seen in aircraft electrical system maintenance, especially when working with capacitors, filters, ignition systems, and circuits that briefly store or smooth electrical energy.
Derivation
From the Latin 'capacitas,' meaning 'capacity' or 'ability to hold.' The word literally describes the holding capacity of a part — in this case, for electrical charge rather than liquid or volume.
Why Pilots Care
Capacitance is the working principle behind capacitor-type fuel quantity systems found on many aircraft. Understanding it helps technicians troubleshoot fuel gauging, ignition, and avionics circuit faults correctly.
Analogy
Think of a capacitor like a small bucket for electricity. Capacitance is the size of the bucket — how much charge it can hold before it's full.
Intuition Check
Capacitance does not mean general storage capacity like a fuel tank or baggage area. It specifically means the ability to store electric charge in a circuit.
Example Sentence 1
The capacitance of the fuel tank probes changes as fuel level rises, and the gauge translates that change into a fuel quantity reading.
Example Sentence 2
High capacitance in a wiring harness can cause unwanted signal interference in the radio.