Definition
A capacitor that uses a thin oxide layer formed on a metal plate (typically aluminum or tantalum) as its dielectric, with a conductive electrolyte serving as the second plate. This construction produces a very high capacitance in a small physical size, but the capacitor is polarized — it must be installed with correct positive and negative terminal orientation, or it can fail, leak, or rupture.
Plain English
A small electrical part that stores a relatively large amount of electrical charge for its size. It only works when wired in the right direction — the positive and negative ends matter.
Context Anchor
Seen in aircraft maintenance and electrical-system discussions, especially inside radios, power supplies, and other electronic units.
Derivation
From 'electrolyte' (a conductive liquid or paste that carries electric current) plus 'capacitor' (a device that stores electric charge). The name reflects that the second 'plate' is actually a conductive electrolyte rather than solid metal.
Why Pilots Care
These capacitors stabilize voltage and reduce electrical noise that could affect instruments or radios.
Intuition Check
Do not think of an electrolytic capacitor as just any capacitor. The key points are that it uses an electrolyte, can store a lot of charge for its size, and usually must be connected in the correct direction.
Example Sentence 1
The technician traced the radio's power supply fault to a failed electrolytic capacitor that had leaked onto the circuit board.
Example Sentence 2
Voltage spikes during engine start were reduced once the electrolytic capacitor was replaced.