Given, length of rods are L and 2L. Coefficient of linear expansion α and 2α. As, we know that, Δl=loαΔT where, Δl is change in length, T is temperature and l0 is initial length let final heat coefficient be α′ ∴(L+2L)α′ΔT=LαΔT+2L.2α.ΔT ⇒3α′=α+4α=5α ⇒α′=
