A metal vessel is used to keep liquid chemical reactants hot. The metal vessel has thick walls. A liquid reactant at a temperature of 150∘C150^\circ\text{C}150∘C is maintained inside.
The outer surface of the vessel gets hot. Some thermal energy passes through the metal walls because vibrating atoms in the metal lattice collide with neighbouring atoms and transfer energy. Explain how the rest of the thermal energy is conducted through the metal walls by another process.
The outer surface of the vessel is coated with a bright, highly polished silver finish. Explain how this surface finish reduces the rate of energy transfer to the surroundings, thereby reducing the input power required to keep the reactants at 150∘C150^\circ\text{C}150∘C.
The vessel is designed to be spherical. A sphere has a smaller surface area than a cylindrical vessel of the same volume. Explain the thermal advantage of this spherical shape.
62 exam-style questions on CIE IGCSE Physics 2.3.4 Consequences of thermal energy transfer. Each one has a worked solution and a mark scheme showing where the marks go.