Energy Transfer Conductivity Radiation

Conduction, Convection, Radiation

By Erin Hannan

What we will cover ​

• definitions

• ​examples

• ​what you need to know for your assessment

​Heat and Heat Transfer

​Heat (or thermal) energy is the result of particle movement and generates heat.

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Heat transfer occurs ​when heat energy transfer from one particle to another.

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At a particle level, as particles heat up they start to move faster, they collide with each other, and the space between them increases. ​

​3 Types of Heat Transfer

​Conduction

• ​when particles are touching each other

Convection

• ​only occurs in fluids (liquids and gases)

• circular movement

Radiation

• ​heat travelling in waves through air or a vacuum

​Conduction

​Conduction is a form of heat transfer, and occurs when particles are touching

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Examples:

• ​metal spoon being heated in a cup of tea

• pot being heated on stove

• ​heat conducting through ceiling, windows, and walls into your house

​Convection

​Convection is a form of heat transfer, that only works in fluids (liquids or gases).

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Heat source heats the bottom of the fluid, as it heats up the particles move further apart and become less dense, then the cooler water is more dense and falls to the bottom. Where it is then heated and will rise.

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'Hot air rises'

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Examples:

• cooling a room with air conditioner

• boiling a pot of water​

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​Radiation

Radiation is a form of heat transfer that does not need particles to travel through. Heat travels in waves, and can move through air and space.

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Examples:

• he​at from a fire

• heat from the sun heating up outside of house

​Things to Note

​These will often combine - it is not as simple as it is made out to be.

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For example:

A room is heated by radiation by a fire, but the entirety of the room is heated by convection, and specific objects within the room will be heated by conduction. ​

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Heat transfer can be impaired by an insulator. This is a material that does not conduct heat well, for example, ​rubber, glass, or wood.

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​Assessment Tips

​You need to include a components of your house that use conduction, convection, and radiation; and you need to suggest improvements to increase thermal efficiency.

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Thermal efficiency is ​how much heat is retained or removed compared to how much energy it took to complete.

For example; a house that is not very thermally efficient will have to use a lot of electricity (through air conditioners and heaters) to remain at an optimal living temperature. ​

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Research components of your house that contribute to heat transfer. ​

Multiple Choice

How does heat move?

• In many directions

• from warm places to cooler places

• from cold places to warm places

• Both B and C

Multiple Choice

If you burn your hand on the handle of a hot pot, heat was transferred to your skin by

• conduction

• convection

• radiation

• equilibrium

Multiple Choice

A material that reduces the flow of heat is a(n)

• conductor

• insulator

• metal

• radiator

Multiple Choice

Energy from the Sun travels to Earth as

• Conduction

• Convection

• Insulation

• Radiation

Multiple Choice

What type of thermal energy transfer is number 2 pointing to?

• Convection

• Conduction

• Radiation

• Insulation