Question

A wire of resistivity r is stretched to double its lenght .how does it affect the (a)resistance (b)resistivity

Answer 1

As we know that the Resistance of wire is qual to r*l/A (where r is resistivity of wire, l is length of wire and A is area of cross-section of wire.)

(a) Above observation shows that R(Resistance) is directly proportional to length^2 and indirectly proportional to area^2 that means when length of wire stretched to double then R will also increased to four times.

(b) Resistivity is material property it is same in same material.