__________ is the passing of kinetic energy through the collision of particles or ions. This happens best when particles are close together as they are in solids. Or when there are free electrons that can diffuse through the material, as in metals.
__________ is the mass movement of particles with kinetic energy. This requires the particles to be able to move past each other as they can in a fluid. The __________ currents are normally due to warm, less dense fluid rising. A fan oven uses forced __________ to equalise the temperature throughout it. Stirring is another example of forced __________.
__________ is electromagnetic waves that do not require a medium to travel through. Dark objects are the best emitters and absorbers of infra-red __________.