# Physics help...

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Thread starter 6 years ago
#1
I don't understand conduction, convection, and radiation.
I THINK conduction is when an object is heated and the particles gain more energy; they begin to vibrate and pass this energy onto other particles until the vibrations reach the other end of the object.
Radiation...? It is emitted by the sun and...
I just don't know how to apply it when it comes to an exam question, for example, when I am asked how heat is lost by convection, conduction, and radiation through a house. Any help would be appreciate and thank you in advance.
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6 years ago
#2
(Original post by Wolfram Alpha)
I don't understand conduction, convection, and radiation.
I THINK conduction is when an object is heated and the particles gain more energy; they begin to vibrate and pass this energy onto other particles until the vibrations reach the other end of the object.
Radiation...? It is emitted by the sun and...
I just don't know how to apply it when it comes to an exam question, for example, when I am asked how heat is lost by convection, conduction, and radiation through a house. Any help would be appreciate and thank you in advance.
Hiya,

Radiation in this case is energy is transferred to cooler surroundings by way of an hot object emitting electromagnetic waves that would be at the infrared end of the electromagnetic spectrum.
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6 years ago
#3
In a house:
Conduction is the transfer of heat energy through a material - without the material itself moving. For example, it is lost through windows, door ect

Convection is the transfer of heat energy through a moving liquid or gas. For example, some cold air could enter through a gap in the door.

Radiation is energy carried by particles from a radioactive substance, or spreading out from a source which causes heat energy to leave the house through walls, roofs ect
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6 years ago
#4
- Conduction occurs mainly in solids where vibrating particles pass on their extra kinetic energy to neighbouring particles. Conduction is faster in denser objects as there are more particles in the space to pass on energy.

- Convection occurs only in solids and gases when more energetic particles move from a hotter region to a colder region (taking the heat with them). A household radiator is a good example of this as when the cool air by the floor is heated, it rises as it gets less dense. Because the air is no longer near the radiator, it sinks (as it is more dense) and then moves back down to the radiator, being heated once more and the process repeats in a circle.

- Infrared Radiation is emitted by all objects from the surface of the object. The hotter the object, the more radiation it emits. Infrared radiation is on the electromagnetic spectrum (which includes gamma rays, visible light and radio waves) so can be detected using certain technologies (from a distance). It is absorbed by black matte surfaces and reflected by white shiny surfaces.

Thats about all I know but I hope it helped!
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