A vacuum flask has a double-walled container with a vacuum in the space between the inner and outer walls.
How is thermal energy transferred across this vacuum space?
by conduction only
by convection only
by radiation only
by conduction and convection
62 exam-style questions on CIE IGCSE Physics 2.3.4 Consequences of thermal energy transfer. Each one has a worked solution and a mark scheme showing where the marks go.