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 ___________________________
____________________
______________________
________________