Heat Transfer Conduction, Convection, and Radiation

Three Heat Transfer Situations Conduction Convection Radiation

Basic Guidelines – Heat and Particle Movement Relationship

Heat Transfer Heat transfer is the movement of thermal energy from a warmer item to a cooler item. Remember, heat moves in predictable ways, from a high to a low.

Heat and Temperature Animated This simple animation shows what happens to these spheres (blue and yellow) when the temperature moves from 0 degrees Kelvin to 300 degrees Kelvin. Note the speed of the smaller (yellow) particles increases faster than the larger (blue) ones.

Conduction Conduction is heat transfer through solids. Examples: Your feet transfer (conduct) heat to a cold tile floor A spoon placed in hot soup becomes warmer as the spoon conducts heat away from the hot soup

Conduction examples

Convection Convection occurs in fluids A fluid is defined as a liquid or gas because fluids have the ability to flow from one place to another Solids, however, maintain their position

Convection continued Consider this - when you look at the road in the summertime on a hot day, you may notice that the air above the road looks “blurry” – this is convection taking place as the hot air directly over the road absorbs the heat from the road and rises. Although the explanation can be quite complex, convection can help explain why mirages are seen in the desert.

Convection and Earth Science Connection

Radiation Question: If conduction deals with solids and convection deals with fluids, how does heat arrive to Earth from the Sun? There is very little matter in between the Earth and Sun.

Radiation Diagram

Radiation continued Heat can travel in waves without a medium (a liquid, solid, or gas). Radiation is the term that describes heat movement without a medium of matter.

The Electromagnetic Spectrum

Radiation continued All of the forms of electromagnetic energy in the spectrum can travel through the universe as waves – we call this radiation.

Temperature The measure of the average kinetic energy of the individual particles in matter. Temperature scales: –Fahrenheit Freezing = 32° F Boiling = 212° F –Celsius Freezing = 0° C Boiling = 100° C

Temperature The Kelvin Scale –Used in physical science. –Same degree intervals as Celsius Freezing = 273 K Boiling = 373 K –Absolute zero 0 K = -273°C Lowest possible temperature No more thermal energy can be removed

Thermal Energy &Heat Objects contain thermal energy –Total energy of all of the particles in an object Heat is thermal energy moving from a warmer object to a cooler object

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