JEE Advanced Model Paper 16 with solutions for online practice

Ends of two wires A and B having resistivity ρA = 3 × 10−5 Ωm and ρB = 6 × 10−5 Ωm. ofsame cross section area joined in series together to form a single wire. If the resistanceof the joined wire does not change with temperature, then find the ratio of their lengths

lA

lB

, given that temperature coefficient of resistivity of wire A and B is αA = 4 × 10−5 / °C and αB = - 6 × 10−6 / °C . Assume that mechanical dimensions do not change withtemperature