# Temperature and energy transfer

Temperature and energy transfer

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## Temperature/energy transfer

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. This means that thermal energy transfer by radiation can even work in space.

Radiation is how we feel the heat of the sun. Infrared cameras give images even in the dark because they are detecting heat not visible light.

Temperature is the measure of energy per particle.

Differences in temperature can lead to transfer of energy.

Energy can be transferred through conduction, convection and evaporation.

Insulation can reduce transfer of energy from hotter to colder objects.

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Substances that allow thermal energy to move through them easily 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.

Conduction:When a substance is heated, the particles gain energy&vibrate more. The particles bump into nearby particles and make them vibrate more. This passes the thermal energy through the substances from the hot end to the cold end.

Convection:The particles in liquids&gases can move from place to place. Convection happens when lots of thermal energy in a liquid or gas is transferred&takes place of the particles with less thermal energy. Thermal energy is transferred from hot places to cold places by convection.

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Heat&temperature are not the same thing.

The temperature of an object is to do with how hot or cold something is. Eg. A swimming pool is 30 degrees Celsius& a cup of tea is 80 degrees Celsius. The swimming pool contains more water so it stores more thermal energy than the cup to tea.

Electrical energy: Batteries transfer stored chemical energy as electrical energy in moving charges in wires. Electrical energy is transferred to the surroundings by the lamp as light energy&thermal energy.

Kinetic energy: Moving things have kinetic energy. The heavier something is the more kinetic energy it has. All moving things have kinetic energy

Sound energy: A plucked guitar string transfer energy into the air as sound, Kinetic energy from the moving air molecules transfers the sound energy into your ear drum.

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Thermal energy: Thermal energy comes from heat. Hot tea has thermal energy. Some of this energy is transferred to the particles in cold milk which you pour into tea to make the tea cooler.

Chemical energy: Chemical reactions releases energy. When an explosive goes off chemical energy stored in it transferred to the surroundings as thermal, sound&kinetic energy.

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