Question

The resistance of a metal wire of length 3 m is 60 Ω. If the area of cross-section of the wire is 4×10⁻⁷ m², calculate the electrical resistivity of the wire.

State how would electrical resistivity be affected if the wire (of part 'ii') is stretched so that its length is doubled. Justify your answer.

Define one ampere.

The resistance of a wire of 0·01 cm radius is 14 Ω. If the resistivity of the material of the wire is 44 × 10⁻⁸ Ωm, find the length of the wire. (Given π = 22/7)