The clamp-on AC ammeter consists essentially of a split-core and a rectifier-type instrument connected to the secondary winding of a particular type of transformer. Which type is used?

Correct Answer: Option C — current transformer

Clamp-on AC ammeters utilize an integral current transformer (CT). The split-core acts as the magnetic core, with the conductor under test serving as a single-turn primary winding, stepping down high alternating currents safely to a proportional value readable by the rectifier instrument.