The resistivity of copper metal depends on only one of the following factors. This factor is :

The resistivity of a certain material is 0.6 Ωm. The material is most likely to be:

When the area of cross-section of a conductor is doubled, its resistance becomes:

If the area of cross-section of a resistance wire is halved, then its resistance becomes :

A piece of wire of resistance 20 Ω is drawn out so that its length is increased to twice its original length. Calculate the resistance of the wire in the new situation.