Coefficient of linear expansion of brass and steel rods are (α1 and α2. Lengths of brass and steel rods are l1 and l2, respectively. If (l2-l1) is maintained same at all temperatures, which one of the following relations holds good? [NEET 2016]

According to question,Coefficient of linear expansion of brass = α1Coefficient of linear expansion of steel = α2Length of brass and steel rods are l1 and l2 respectively.As the increase in length (l'2-l'1) is same for all temperatures.So,                     l'2-l'1 = l2-l1⇒l21+α2Δt-l11+α1Δt=l2-l1⇒l2α2=l1α1