Transfer of Heat Energy http://www.wisc-online.com/objects/index_tj.asp?objID=SCE304 Radiation is the transfer of energy by waves traveling in all directions from its source. It is also the transfer of heat energy by electromagnetic wave motion. The transfer of energy from the sun is accomplished primarily by radiation. With radiation, the energy does not have to travel through something like a metal conductor or water, it is just transferred by waves. Because of radiation, the sand heats up on a hot summer day. A microwave oven cooks food because of the transfer of energy by radiation. Convection is the transfer of heat by movement of molecules from one place to another in a gas or a liquid. Convection currents are responsible for making changes in the atmosphere which influence the weather. Convection is responsible for making macaroni rise and fall in a pot of heated water. The warmer portions of the water are less dense and therefore rise. When the warm water reaches the top, it starts to cool down. As it cools, it becomes more dense and falls back to the bottom of the pot. Conduction is the transfer of energy from one molecule to another. For example, a spoon in a cup of hot soup becomes warmer because the heat from the soup is conducted along the spoon. When you put a pan on the stove to make a grilled cheese sandwich, the heat from the stove transfers energy to the pan, making its molecules move faster. Some of these molecules bump into the molecules in the bread and so energy is transferred to the sandwich. Even though conduction is a transfer of kinetic energy from particle to particle, the molecules do not travel from one place to another. They move in place and bump into each other to transfer energy. Word Radiation Convection Conduction Definition Picture Use the words conduction, convection, or radiation to complete the following statements. 1. The top floor of your house gets warmer because of ________________________ 2. Your hand getting burned because you put it on the burner is __________________ 3. Convection happens because hot air or water ___________________________ and cold air or water ________________________________ 4. _________________ is energy that travels by waves in all directions from its source. 5. The transfer of kinetic energy from one molecule making direct contact with another molecule is called ___________________________________ 6. _________________ transfers thermal energy by the movement of molecules from one place to another in a gas or liquid. 7. The sinking of cold water and forcing up warm water is ____________________ 8. A metal spoon getting hot because it is sitting in a bowl of hot soup is __________________________ 9. The movement of heat in a microwave is _______________________________ 10. Using a hot iron to iron your wrinkled pants is __________________________ 11. Cooking marshmallows over a fire is __________________________________ 12. The sidewalk being heated by the sun is ________________________________ 13. The frying of eggs in a frying pan is ____________________________________ 14. How does the Sun’s energy reach Earth? ______________________________ 15. Hot air circulating around a cake to cook it is ___________________________ ____________________ ______________________ ________________