Question:

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?

α₁l₂ = α₂l₁

α₁l₂² = α₂l₁²

α₁²l₂ = α₂²l₁

α₁l₁ = α₂l₂

Both the rods will have same change in length. ⇒ Δl₁ = Δl₂ ⇒ l₁α₁ΔT = l₂α₂ΔT ⇒ l₁α₁ = l₂α₂