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Transcript
Heat and temperature are not the same thing, although both are concerned with
thermal energy.
Heat
The heat an object contains is the amount of its thermal energy, measured in joules
or J.
Temperature
The temperature of an object is to do with how hot or cold it is, measured in degrees
Celsius. Note that the unit of temperature is written as °C, (not °c or
oC
).
A thermometer is used to measure the temperature of an object
A thermometer is used to measure the temperature of an object
Let's look at two examples to see the difference between heat and temperature.
Example 1
A swimming pool at 30°C is at a lower temperature than a cup of tea at 80°C. But the
swimming pool contains more water, so it stores more thermal energy than the cup of
tea.
Example 2
To boil water we must increase its temperature to 100°C. It takes longer to boil a large
beaker of water than a small beaker because the large beaker contains more water and
needs more thermal energy to reach 100°C.
Thermal energy can be transferred by:

conduction

convection

radiation
Conduction
When a substance is heated, its particles gain energy and vibrate more vigorously. The
particles bump into nearby particles and make them vibrate more. This passes the
thermal energy through the substance by conduction, from the hot end to the cold end.
Stages in conduction
This is how the handle of a metal spoon soon gets hot when the spoon is put into a hot
drink.

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 insulators.
Convection
The particles in liquids and gases can move from place to place. Convection happens
when particles with a lot of thermal energy in a liquid or gas move, and take the place of
particles with less thermal energy. Thermal energy is transferred from hot places to cold
places by convection.
Radiation
All objects transfer thermal energy by infrared radiation. The hotter an object is, the
more infrared radiation it gives off.
No particles are involved in radiation, unlike conduction and convection. This means that
thermal energy transfer by radiation can even work in space, but conduction and
convection cannot.

Radiation is how we can feel the heat of the Sun, even though it is millions of
kilometres away in space.

Infrared cameras give images even in the dark, because they are detecting heat,
not visible light.
Conduction and convection need moving particles to transfer the thermal energy, but
radiation does not.
http://www.bbc.co.uk/schools/ks3bitesize/science/energy_electricity_forces/energy_transfer_stora
ge/revise1.shtml