Models of Energy Transfer – Practice
1) Explain the difference between conduction and convection in terms of the particles in solids, liquids and gases:
2) Explain the difference between conduction and convection when compared to radiation:
3) Copper is a better conductor than stainless steel but it is more expensive. Why do stainless steel saucepans sometimes have a copper base?
1) Conduction takes place in solids where particles have fixed positions. When particles are heated their kinetic energy increases, resulting in larger vibrations. The particles do not move from their mean position. In conduction, when particles vibrate they pass this energy on to neighbouring particles and so on
Convection takes place in liquids where particles are free to move. When particles are heated their kinetic energy increases and they will move faster and occupy more space. Liquids and gases that are warmer will expand and become less dense than those which are cooler. Particles will then move from warmer to cooler areas, transporting heat energy with them
2) Conduction and convection require a medium in order to transfer heat energy. Radiation is the transfer of heat through a vacuum by the propagation of electromagnetic radiation. Electromagnetic radiation that is absorbed will result in a rise in temperature.
3) Stainless steel is generally used as it is cheaper and corrosion resistant. Copper can be used as a base as it can make the saucepan more efficient and effective in cooking.