Electrical Engineering Materials Set 2

low carbon steel ✘ wrought iron ✘ cast iron ✘ malleable iron ✔

Increases ✘ Decreases ✘ Does not change ✘ Change ✔

Aluminium is a noble metal ✘ Atmospheric oxygen can only diffuse very slowly through the oxide layer which is formed on the surface of aluminium ✘ No reaction with oxygen occurs ft Any of the above ✘ All of the above ✔

Copper-constantan ✘ Aluminium-tin ✘ Silver-German silver ✘ Iron-steel ✔

non-linear conductor ✘ reverse conductor ✘ bad-conductor ✘ non-conductor ✔

Smoky and dirty atmosphere ✘ Humidity in the atmosphere ✘ Both A and B ✘ Neither A nor B ✔

Aluminium is more ductile and malleable than copper ✘ Aluminium is available in plenty, cheaper and lighter than copper ✘ Aluminium has lower resistivity than that of copper ✘ Aluminium has less temperature co-efficient than copper ✔

Less liability to kink ✘ Greater flexibility ✘ Less liability to break ✘ All of the above ✔

The electronic concentration and the mobility of the free electrons ✘ The number of valence electrons per atom ✘ Either A or B ✘ None of the above ✔

Overhead telephone wire ✘ Earth wire ✘ Core wire of ACSR ✘ All of the above ✔