Definition
An electronic resistor made by depositing a thin layer of carbon onto a small ceramic rod, then cutting a spiral groove in the carbon film to set the resistance value. The component is sealed in an insulating coating and fitted with wire leads at each end. Carbon-film resistors are valued for their stable resistance, low electrical noise, and tighter tolerance compared to older carbon-composition resistors.
Plain English
A small electronic part that limits the flow of electricity. It is made by coating a ceramic rod with a thin layer of carbon, which provides the resistance.
Context Anchor
Seen in aircraft electrical and avionics maintenance, especially in circuit diagrams, component lists, and repair descriptions.
Derivation
Carbon refers to the conductive carbon coating that does the actual resisting. Film describes how that carbon is applied -- as a thin layer rather than a solid block. Resistor comes from Latin resistere, meaning to stand against -- the part stands against the flow of electricity, reducing it to a desired level.
Why Pilots Care
Precise resistance values keep instruments, radios, and navigation equipment operating reliably; a failed resistor can produce intermittent or total loss of a system.
Intuition Check
Do not picture a loose sheet of film. In this term, film means a very thin coating of carbon fixed onto the body of the part.
Example Sentence 1
The technician replaced a burned-out carbon-film resistor on the radio's circuit board.
Example Sentence 2
A burned carbon-film resistor in the fuel-quantity circuit caused the gauge to read empty even though the tanks were full.