Which of the following materials are considered ferrous?

Ferrous materials are defined as metals that contain iron, which gives them certain magnetic properties and higher strength. In this context, rigid metal conduit (RMC) and electrical metallic tubing (EMT) are both ferrous materials because they are made from steel, an iron-containing alloy. This characteristic makes them suitable for electrical installations, as they provide structural support and protection for electrical wiring.

Copper conductors, on the other hand, are non-ferrous materials. Copper does not contain iron and is known for its excellent electrical conductivity, which is why it is widely used for wiring and electrical connections.

Thus, stating that RMC and EMT are the only ferrous materials accurately highlights the materials that contain iron while excluding copper, which does not.