How to distinguish steel plate, aluminum plate and copper plate from appearance

Aluminum and copper are non-ferrous metals, copper is yellow and aluminum is white. Steel is a ferrous metal (because the surface of steel is usually covered with a layer of black iron oxide, so get this name) steel plate is divided into cold rolled sheet metal and hot rolled sheet metal, hot rolled sheet metal on the oxidized skin is good to distinguish between the cold rolled sheet metal with a bright surface and hard texture. The density of steel plate is much greater than the density of aluminum, the same size of the two pieces of sheet metal, the weight difference is very large. In addition, a magnet can also be used to judge the two pieces of sheet metal, the magnet attracts iron, does not attract aluminum.