Heat Transfer

1. Heat Transfer Ch.3, sec 2

2. Radiation • The transfer of heat or energy through space. • Radiation takes place with no direct contact between heat source and an object.

3. Radiation:  Sit by a sunny window.  Do you feel the warmth of the sun on your skin?  This is radiant heat or solar radiation.  You can also find this in toasters and electric ovens with heating elements.  The heat from the elements is radiant heat and this is what cooks the food.  An element on an electric stove does the same thing.  

4. Examples • Light • Sun • Microwave Oven • Cancer treatments

5. Conduction • The transfer of heat within or between materials that are touching.

6. Conduction: Pour hot water into a tea cup and feel the heat conducting through the tea cup. This is conduction.  You can also feel the cold when you have a glass of ice water and the cold comes through the glass.  

7. Examples • A cup • Pots & pans • Heating pad

8. Convection • The transfer of heat by the movement of currents with in the fluids- liquids and gases. The flow transfers heat from one part of the fluid to another.

9. Convection: This is a little harder to see but if you have ever watched a pot on the stove boil, then you are seeing convection occuring.  What happens is that cold water or air sinks (because it is heavier then hot water or air) and the hot water or air rises.  As it rises it cools down and sinks.  This creates a circulation we call convection.

10. Examples • Heater • Fire • Steam