An iron rod is heated at one end. Which of the following best describes the physical mechanisms responsible for the conduction of thermal energy to the cooler end?
the migration of high-energy iron ions from the hot end to the cold end representing a flow of matter
only the vibrations of the iron ions in the lattice structure
both the vibration of iron ions in the lattice and the movement of free (delocalized) electrons along the rod
only the movement of free (delocalized) electrons along the rod
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.