(a) Define electrical resistivity and electrical conductivity of a material. (b)…
PHYSICS · Subjective · CBSE · Physics · Current Electricity · Current Electricity
Problem
(a) Define electrical resistivity and electrical conductivity of a material.
(b) State the SI unit of each quantity.
(c) Metals and constantan (a Cu–Ni alloy) are both used in electrical circuits but for different purposes. Describe qualitatively how the resistivity of (i) a typical metal and (ii) an alloy such as constantan varies with temperature from room temperature up to about 500K.
(d) Sketch two separate graphs on the same set of axes to represent the variation you have described in part (c), labelling the curves clearly.
(e) Explain on the basis of your answer to parts (c) and (d) why alloys rather than pure metals are chosen for making standard laboratory resistors.