An industrial steel reservoir is used to store molten wax at 95∘C95^\circ\text{C}95∘C. The steel walls of the reservoir are thick.
Part of the thermal energy is transferred through the steel walls because vibrating atoms collide with neighboring atoms. Explain how the rest of the thermal energy is conducted through the steel wall to the outer surface by a different process at the microscopic level.
The outer surface of the reservoir is finished with a highly polished, shiny chrome plating. Explain how this shiny surface reduces the electrical power required to keep the wax at 95∘C95^\circ\text{C}95∘C.
The steel reservoir is spherical. A sphere has a smaller surface area than a cylindrical reservoir of the same volume. Explain the advantage of using a spherical reservoir rather than a cylindrical one.
301 exam-style questions on CIE IGCSE Physics 2.3 Transfer of thermal energy, covering 2.3.1a Thermal conductors and thermal insulators, 2.3.1b Explaining thermal conduction, 2.3.2 Convection, 2.3.3a Thermal radiation, 2.3.3b Surface colour and texture, 2.3.3c Rate of emission and absorption of radiation, and 2.3.4 Consequences of thermal energy transfer. Each one has a worked solution and a mark scheme showing where the marks go.