Definition 1 of 2
Definition
A coil of wire wound around a ring-shaped (donut-shaped) iron or ferrite core, used in aircraft electrical and electronic circuits as an inductor or transformer. The closed-loop core keeps the magnetic field largely contained within the ring, which gives high inductance for the size and reduces electromagnetic interference with nearby components.
Plain English
It is a wire wrapped many times around a donut-shaped core. That shape traps the magnetic field inside the donut, so the part works efficiently and does not leak interference into other equipment around it.
Context Anchor
Seen in aircraft electrical and avionics components such as transformers, filters, and current-sensing devices during maintenance or troubleshooting.
Derivation
Toroidal comes from the Latin torus, meaning a rounded swelling or cushion — the same word geometers use for a donut shape. Calling the coil toroidal simply tells you the core is a closed ring rather than a straight bar.
Why Pilots Care
Helps reduce electromagnetic interference that could affect navigation and communication equipment.
Analogy
Picture wrapping string evenly around a doughnut. A toroidal coil is similar, except the “string” is insulated wire and the shape helps keep the magnetic effect inside the ring.
Intuition Check
Do not picture a loose spring-shaped coil. In this term, the key idea is a coil wrapped around a closed ring.
Example Sentence 1
The technician replaced a toroidal coil in the power supply after tracing a filtering fault.
Example Sentence 2
A toroidal coil in the aircraft's power converter keeps magnetic fields from disrupting nearby radios.