Thermal Energy Transfer Study NotesThermal Energy naturally movesfrom a substance with a highertemperature to a substance with alower temperature, until the twosubstances have the sametemperature
Humans have invented many technologies that transfer energyfrom one object to another or from one place to another.For example, we use furnaces to heat our homes, and refrigeratorsto cool our food.Technology allows us to control the rate of heating and coolingbut not reverse its direction.
Conduction•Conduction is the transfer of thermal energythrough a substance, or between substances incontact•This energy is caused by the collision of the fastmoving particles(hot object) with the slowermoving particles(cold object).•Conductors, such as metal, transfer energy easily.Insulators such as foam or wood, reduce thetransfer of energy.•Think about your coffee keeper. What did you doto stop the transfer of energy through conduction.
Convection•Convection is the transfer of thermal energycaused by the flow of a fluids particles (gas orliquid).•The continuous movement of warmer andcolder soup in a pot is an example of convection.•The hot, less dense soup moves up to thesurface where it cools. The cool soup is nowmore dense and sinks back to the bottom of thepot. The movement creates convectioncurrents.
Convection in the environment•Just as uneven heating of soup on a stove can produceconvection currents, uneven heating of the air can produceconvection currents called “wind.”•Near a lake, the air above the water is colder than the air abovethe land. The warm air particles above the land move fasterand spread apart. This makes the air above the land less dense(lighter) than the air over the water.•Thunderstorms, ocean currents and the movement of theearth’s crust also result from convection currents.
Radiation•Radiant energy is the energy that travels in the form ofelectromagnetic waves, including visible light, ultravioletrays and x-rays, for example.•Radiation is the transfer of radiant energy by means ofelectromagnetic waves.•Unlike the other two ways of transferring thermal energy,•Particles are not involved in the transfer of radiant energy,meaning radiant energy may travel through empty space.•Sources of radiant energy include the sun, candle flames,and stove elements, for example
•Think about your coffeekeeper. What did you do tostop the transfer of thermalenergy. Which type(s) of heattransfer did your inventionbest slow down. Explain how?