| Conductivity is the measure of the ease at which an electric charge or heat can pass through a material. A conductor is a material which gives very little resistance to the flow of an electric current or thermal energy. Materials are classified as metals, semiconductors, and insulators. Metals are the most conductive and insulators (ceramics, wood, plastics) the least conductive. |
| Electrical conductivity tells us how well a material will allow electricity to travel through it. Many people think of copper wires as something that has great electrical conductivity. | 
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| Thermal conductivity tells us the ease upon which thermal energy (heat for most purposes) can move through a material. Some materials like metals allow heat to travel through them quite quickly. Imagine that with one hand you are touching a piece of metal and with the other, a piece of wood. Which material would feel colder? If you said, "metal," you would be correct. But, in fact, both materials are in fact the same temperature. This is relative thermal conductivity. Metal has a higher heat transferability, or thermal conductivity, than wood, letting the heat from your hand leave faster. If you want to keep something cold the best idea is to wrap it in something that does not have a high heat transferability, or high thermal conductivity, this would be an insulator. Ceramics, and polymers are usually good insulators, but you have to remember that polymers usually have a very low melting temperature. That means if you are designing something that will get very hot the polymer might melt, depending on its melting temperature. | |
Electrical and thermal conductivity are closely related. For the most part good electrical conductors are also good thermal conductors.Many products will contain both conductors and insulators- the conductors take the electricity or thermal energy where it is wanted and the insulators prevent it from getting where it isn't wanted. |
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Silver has the highest electrical conductivity of all metals. In fact, silver defines conductivity - all other metals are compared against it. On a scale of 0 to 100, silver ranks 100, with copper at 97 and gold at 76. Because of this property, and because it doesn't spark easily, silver is commonly used in electrical circuits and contacts. Silver is also utilized in batteries where dependability is mandatory and weight restrictions apply, such as those for portable surgical tools, hearing aids, pacemakers and space travel. |
http://www.physics4kids.com/files/elec_conduct.html
Lesson plan for teachers about conductivity- http://www.infinitepower.org/pdf/09-Lesson-Plan.pdf
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