Heat Energy Transfer

Conduction, Convention & Radiation

Essential Standard

• 6.P.3 Understand characteristics of energy transfer and interactions of matter and energy.

Clarifying Objective

• 6.P.3.1 Illustrate the transfer of heat energy from warmer objects to cooler ones using examples of conduction, radiation and convection and the effects that may result.

Essential Questions

• What are the different ways that energy be transferred?

Heat Transfers

• Heat atoms are always looking to try to find cold atoms

• Heat atoms can give cold atoms their heat 3 different ways

• These 3 ways are called ① Conduction ② Convection③ Radiation

Why Does Heat Transfer

• Heat transfers from object to object because EVERY OBJECT IS TRYING TO BECOME WARMER

• Objects try to become what the dominate temperature is (room)

Conduction

• Conduction is the first way atoms with heat in them will transfer them to cold atoms

• Conduction is the heat transfer of two solids joined together through a conductor (direct contact)

Conduction

• A conductor is what actually what actually transfers the heat from one solid to another solid

• Conduction mediums are always solids (they only transfer heat through solids)

Conductor

• Conductors are mediums that will transfer heat from one solid to another

• Hot atoms move through the conductors to transfer their heat to cold atoms

• Some items are better conductors than others

Conductor• Solids are always the best

conductors because their atoms are attached and not spread out so the heat can move through them better

• Gases are the worst conductors because their atoms are so spread out and it will take longer for them to bump into each other

• Metals are the best conductors because they are solids and their atoms have the most density

How Does Conduction Happen?

① Solid with hot atoms look for cold solid atoms

② The conductor is placed between the solid hot atoms & the solid cold atoms

③ Hot atoms (excited) vibrate & hit each other & move through the conductor

How Does Conduction Happen?

④ Once the hot atoms have moved through the conductor they contact the cold atoms of the other solid

⑤ They transfer the heat from their atoms (hot atoms) to the cold atoms and warm them up

⑥ Now all atoms in both solids are warm

Conduction (Example)

• http://www.youtube.com/watch?v=Gyj444FK0zs

Convection

• Convection is the moving of heat through gas or liquid mediums

• Convection will only transfer heat through gasses or liquids

Convection Process

• http://www.youtube.com/watch?v=liKcJKjvFcY

• 0:00-1:36

How Does Convection Happen?

① Hot atoms form and become excited and start to vibrate

② As they vibrate the hot atoms rise because the atoms begin to separate and become less dense

③ The hot atoms that rise push the cold atoms to the bottom and they are heated

How Does Convection Happen?

④ Then those atoms rise and push the next batch of cold dense atoms to the bottom to be warmed again

⑤ The process continues and forms a CONVECTION CURRENT

Convection Example

• http://www.youtube.com/watch?v=Gyj444FK0zs

Radiation• Transfer of heat atoms through

electromagnetic wave motion

• Radiation involves light photons not atom particles

• All waves on the Electromagnetic Spectrum will transfer heat through radiation

① Radio Waves② Microwaves③ Infrared Waves④ Ultraviolet Waves⑤ X-Ray Waves⑥ Gamma Waves

Electromagnetic Spectrum

Radiation (Heat Absorption)• About 50% (half) of the

radiation heat transfer comes from VISIBLE LIGHT part of the spectrum

• The amount of heat absorbed through radiation depends on…

① Intensity of the waves (visible waves are most intense)

② Color of the object the radiation wave is hitting

• This is why darker colors absorb more heat than lighter colors

How Does Radiation Happen?

① Waves from the Electromagnetic Spectrum radiate heat

② The electromagnetic waves carry the heat through any medium

③ The heat waves hit the object and warm it up

Radiation Example

• Campfires radiate heat through light waves from the electromagnetic spectrum

• Microwaves do the same thing

Radiation Video

• http://www.youtube.com/watch?v=GYUN8o4eJ24

Essential Questions

• Get with a partner and answer…

• What are the different ways that energy be transferred?

Important Points• Heat transfer occurs because all

objects are trying to become warmer

• Conduction is heat transferring through direct contact between objects

• Conduction must have conductors to occur

• Metals are good conductors because their atoms are close together

• Conduction only occurs through two SOLIDS

• Convection is heat transfer through currents

• Convections currents occur in liquids & gasses only

• Radiation is the transfer of heat through photons on waves

• It does not include atoms

• Radiation depends on how INTENSE the wave is & the COLOR of the object it is warming