Transcript Conduction - Noadswood Science

Conduction
D. Crowley, 2008
Conduction
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To know how energy travels by conduction, and to understand
the terms conductor and insulator
Temperature
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It is necessary to know some common temperatures we come
across – using the worksheet colour in the thermometer
readings for the six temperatures
Temperature: In a room: 25ºC
In a fridge: 5ºC
In a freezer: -18ºC
Boiling point of water: 100ºC
Freezing point of water: 0ºC
Freezing point of dilute salt solution: -8ºC
Temperature & Heat
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Remember: -
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Heat is a form of energy
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Temperature is a measurement of that energy
Thermal (Heat) Energy
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Thermal (heat) energy is one of the forms of energy
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The types of energy are: 
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Electrical energy - a current in a circuit etc…
Light energy - from the sun; a light bulb etc…
Sound energy - from a loudspeaker; a drum etc…
Kinetic (movement) energy - anything which moves!
Nuclear energy - transferred during a nuclear reaction
Thermal (heat) energy - transferred from hot to colder objects
Radiant heat (infra red) energy - transferred as electromagnetic
radiation by hot objects
Gravitational potential energy - possessed by anything with the
ability to fall
Elastic potential energy - stretched springs; elastic and rubber
bands etc…
Chemical energy - possessed by food; fuels; batteries etc…
Heat Transfer
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Thermal energy (heat) moves from one place to another
because of the difference in temperature between them
The energy transfer is always from hot to cold and it can
happen in three ways:  Conduction
 Convection
 Radiation
Demo
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The energy is passed quite differently in these 3 processes: In conduction, energy is passed from atom to atom – like
passing a tennis ball from person to person in a chain to get it
from the left to right side of the room…
In convection, energy is carried around by the particles – like
carrying the tennis ball individually from the left to right side of
the room
In radiation, energy is given off by hot objects, and absorbed by
another – like throwing the tennis ball from one side to the
other!
Conduction
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In conduction energy is passed from atom to atom
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It is the most important type of heat transfer in solids
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Vibrating particles pass on their extra vibrational energy to their
neighbouring particles
Conduction Circus
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Your task is to visit each of the stations and answer the
question posed there…
Station 1
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Different spoons
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How would you describe the 2 materials?
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What are the advantages of using a plastic spoon and a metal
spoon?
Station 2
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Different blocks
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Describe what you feel when you touch the different blocks
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Are all the blocks the same temperature – they have all been
kept in the same place during the night!
Station 3
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Insulators
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Which is the best insulating material?
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How can you tell this?
Station 4
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Insulators
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Feel the three materials – which is the best insulator?
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What do they all have trapped inside
them?
Station 5
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Saucepan
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Look at the saucepan – what are they made in this way?
Conductors & Insulators
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Substances that allow thermal energy to move easily through
them are called conductors - metals are good conductors of
thermal energy
Substances that do not allow thermal energy to move through
them easily are called insulators - air and plastics are good
insulators
E.g. the space shuttle has very
specialised heat shields (10% silica fibre
and 90% space) which can withstand the
huge temperatures without melting
(>1200ºC)