Question

1. A 10kV power transmission wire is being planned between Adelaide and Sydney (1600km). It should have a resistance of 100 W. The material for the wire must be chosen from the candidates below. Which of the materials is not appropriate? From the remaining materials, determine the most cost effective.

Material	Yield stress (MPa)	Thermal Conductivity (W / m K)	Conductivity (Ohm m)	Density (kg / m3)	Cost (/kg)	Appropriate (Yes / No) If no, why?
Copper	180	390	1.68 x 10-8	8900	$5
Polystyrene	40	0.01	2 x 105	1300	$0.03
Glass	400	0.8	3 x 1011	2200	$0.5
Aluminium	100	195	2.65 x 10-8	2700	$1.5

Answer 1

Polystyrene and Glass are not the appropriate material because they have very high resistivity as compared to copper and Aluminium. Which means that they will incur very high power losses.

From copper and Aluminium, we would choose aluminium as it is much cheaper than copper and the difference in their conductivity is also very less. So the apt material would be Aluminium.