Which statement correctly describes the mechanism of thermal conduction by free electrons in a metal?
Free electrons gain kinetic energy at the hot end and drift throughout the metal, colliding with positive metal ions to transfer energy.
Free electrons transfer thermal energy by vibrating about fixed positions, passing vibrations to neighboring electrons.
Free electrons carry thermal energy by bonding with other electrons to form high-energy molecular compounds.
Free electrons remain closely bound to their parent atoms, preventing the net flow of thermal energy.
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.