Two rods (one semi-circular and other straight) of same material and of same cross-sectional area are joined as shown in the figure. The points A and B are maintained at different temperature. The ratio of the heat transferred through a cross-section of a
dQdt = KA △θl , For both rods K, A and △ θ are same
⇒dQdt ∝ 1l So (dQdt)semi circular(dQdt)straight = lstraightlsemi circular = 2rπ r = 2π .