Saved Bookmarks
| 1. |
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.(rho_(Al) = 2.63 xx 10^(-8) Omegam, rho_(Cu) = 1.72 xx 10^(-8) m, relative density of Al = 2.7 , of Cu = 8.9) |
|
Answer» Solution :We KNOW that`R = (rho l )/(A)` As resistance and LENGTH of both wires are same, hence it means that `(rho_(AL))/(A_(Al)) = (rho_(Cu))/(A_(cu))` ` rArr (A_(Al))/(A_(Cu)) = (rho_(Al))/(rho_(Cu)) = (2.63 xx 10^(-8))/(1.72 xx 10^(-8)) = (2.63)/(1.72)` As relative density of Al, `d_(Al)` = 2.7 and of Cu, `d_(Cu) = 8.9` `(m_(Al))/(m_(Cu)) = (A_(Al))/(A_(Cu)) xx (d_(Al))/(d_(Cu)) = (2.63)/(1.72) xx (2.7)/(8.9) = 0.47 ` (APPROX) Thus, aluminium wire is lighter than copper wire. Due to this very reason aluminium wire is preferred for overhead POWER cables because its mass and hence the cost will be comparatively less. |
|