Question

two wires A and B have their resistances, lengths and radii in the ratio 4 : 1 , 2 : 1 and 1 : 3 , respectively. Compare their conductivities.

Answer 1

The radii have a ratio of 2:1, therefore the cross sectional area is of ratio 4:1. The resistance per unit length is therefore 1:4. Because we are told the mass is the same, wire B, the smaller section wire will have to be 4 times as long to have the same mass, neglecting the effects of any insulation on the mass. So the final resistance of B will be 16 times the resistance of A or 544 Ohms. Now please do the rest of your school work yourself. you will gain from it.