One end of a metal rod is placed in contact with a hot heating plate. Thermal energy conducts along the rod to make the other end warmer.
Which of the following statements correctly describes the behavior of the metal at an atomic level that accounts for the majority of this thermal energy transfer?
Ions at the hot end gain kinetic energy and migrate towards the cooler end.
Ions at the hot end expand in size, colliding with neighboring ions to transfer energy.
Free electrons at the hot end gain kinetic energy and diffuse towards the cooler end, colliding with ions along the rod to transfer energy.
Free electrons at the hot end gain energy and travel directly to the cooler end without experiencing any collisions.
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.