A wire of resistance 3 is stretched to twice its original length. The resistance of the new wire will be

Step-by-step solution

Given, resistance, R₁=3 If l is the original length of the wire, then after stretching the length of wire is l^ =2 l From the relation, resistance of a wire, R= l A where, is the resistivity and A is cross-sectional arca. aligned &R l A & R l² V [ A= Volume Length ] aligned aligned & R₁ R₂ = l₁² V V l₂² & Here, l₁=l, l₂=2 l & 3 R₂ = l² 4 l² & or R₂=3 4=12 aligned