question_answer 16)

Two wires of equal length, one of aluminium and the other of copper have the same resistance. Which of the two wires is lighter? Hence explain why aluminium wires are preferred for overhead power cables.   Relative density of Al = 2.7, of Cu = 8.9.)  

Answer:

Aluminium RAI ?AI                 Mass of aluminium wire,                 MA1 = A1l                 Copper                 Mass of copper wire,                                 MCu = ACu l cu                 Then                                     As resistance RAI and RCu are equal,                                 i.e.                                             Aluminium is lighter, so it is used for overhead power cables.