Neco Model Questions Vol1 2019 Physics Question 8

A composite rod consists of a 0.50 m long copper section (thermal conductivity k₁ = 400 W m⁻¹ K⁻¹) joined end‑to‑end with a 0.50 m long steel section (k₂ = 50 W m⁻¹ K⁻¹). Both sections have the same uniform cross‑sectional area A = 1.0×10⁻⁴ m². The left end of the copper is maintained at 100 °C and the right end of the steel at 20 °C. Answer the following: (a) Determine the temperature at the copper–steel junction. (b) Calculate the steady‑state rate of heat transfer through the whole rod. (c) A thin flat layer of insulation (k₃ = 0.04 W m⁻¹ K⁻¹, thickness 0.001 m) is applied around the steel section, covering the same cross‑sectional area. Assuming the end temperatures remain unchanged, estimate the new rate of heat transfer. (d) Discuss qualitatively how increasing the length of the steel section would affect the temperature distribution and the overall heat transfer rate.