A double-walled glass mug contains hot tea and is sealed with a plastic lid. The mug rests on a wooden table. There is a small air gap between the inner and outer glass walls.
Which statement is correct?
The air gap prevents all thermal radiation from escaping.
The table is heated by convection from the bottom of the outer cup.
The lid reduces heat loss by convection.
No heat is transferred through the glass walls because glass is a perfect insulator.
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.