Definition
A fixed-value resistor made from a solid rod of carbon granules mixed with a binder material, with wire leads attached to each end and the body sealed in an insulating coating. The resistance value is determined by the ratio of carbon to binder in the mixture.
Plain English
A small electrical part that resists the flow of electricity by a set amount, made from a packed mix of carbon and binding material rather than a coil of wire.
Context Anchor
Seen in aircraft electrical maintenance, especially in older radios, instruments, and other electronic circuits.
Derivation
Composition' comes from the Latin 'componere,' meaning 'to put together.' The name reflects how the resistor is built — by composing (mixing) carbon with a binder rather than winding a wire. Knowing this helps distinguish it from a 'wire-wound' resistor, which is made differently.
Why Pilots Care
Composition resistors are common in older aircraft electronics. They tend to drift in value with age and heat, which can cause intermittent faults in radios, instruments, and electrical circuits — useful background when troubleshooting unreliable equipment.
Analogy
Think of it like a narrow section in a hose. The hose still lets flow through, but the narrow part limits how much can pass at once.
Intuition Check
Do not read “composition” as a type of writing or paperwork here. It means the resistor is made from a mixed material, not from a wound wire.
Example Sentence 1
The avionics technician replaced an aged composition resistor in the radio that had drifted out of tolerance.
Example Sentence 2
Older aircraft radios often contain composition resistors because they handle low power reliably and are easy to source.