Definition
Electric charges that are free to move through a material, such as the free electrons in a metal conductor or the ions in an electrolyte. Their movement under the influence of an applied voltage constitutes electric current.
Plain English
Tiny electrical particles inside a material that can move around. When they flow, you have electricity moving through a wire or fluid.
Context Anchor
Seen in aircraft electrical, static electricity, fueling, bonding, and grounding discussions.
Derivation
From Latin 'mobilis' meaning 'movable' or 'able to move.' The term simply names what these charges do — they move, as opposed to charges that are locked in place within an atom or molecule.
Why Pilots Care
Knowing how mobile charges behave explains why some materials safely conduct electricity through aircraft circuits while others block it.
Grounding Statement
Picture electrons drifting through a copper wire when a battery is connected — that drift of mobile charges is the current that powers the aircraft's lights, radios, and instruments.
Intuition Check
Mobile charges are not phone fees or service charges. Here, “mobile” means able to move, and “charges” means electrical charges.
Example Sentence 1
When the master switch is closed, mobile charges flow through the wiring to power the avionics.
Example Sentence 2
When an aircraft is struck by lightning, mobile charges redistribute across the skin to equalize the potential difference.