7. A wire of copper having length I and area of cross-section A is taken and a current i is flown through it. The power dissipated in the wire is P. If we take an aluminium wire having same dimensions and pass the same current through it, the power dissipated will be A.P B.< P C.> P D.2P
Option C Solution: Aluminum has a resistivity varying from 2.65 to 2.82 × 10−8 Ω m. The resistivity of copper is generally given as: 1.72 x 10-8 Ω.m. So, since resistivity of aluminium is higher than that of copper, so power dissipated will be greater than P. this is because rest of the factors (l, A and i) are constant.
