A flask is designed to keep a hot beverage warm by minimizing heat loss. Which texture and colour should the outer surface of the flask be to ensure that thermal radiation is emitted at the lowest rate?
dull black
dull white
shiny black
shiny silver
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.