Energy Transfers
3 marks · EasyDescribe a simple experiment you could carry out to show that air is a poor conductor of heat. Include the setup and an observation you would make.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
Set up a small candle at the bottom of a glass jar and seal the jar with a lid. Place your hand on top of the lid. The lid warms very little, showing that air (which fills the jar) is a poor conductor of heat.
Must show: describes air as poor conductor, setup where air is barrier, relevant observation
Also accept: Use two metal rods, one in air, one with a wool cover, and compare heating at the ends.
Common mistakes: Confusing conduction with convection
Show mark scheme and worked solution
Marking points
M1 · 1 mark · Describes a correct setup where a heat source is separated by air from the observer/measurement.
B1 · 1 mark · Mentions that the presence of air means the heat is not transferred quickly.
A1 · 1 mark · Correctly observes/infers that heat is not felt strongly, showing air is a poor conductor.
Worked solution
Light a candle in a glass jar, then seal the top with a metal lid. After several minutes, feel the outside of the lid. It becomes warm very slowly, if at all, because air does not conduct heat well.