金屬之中,導電與傳熱一問？

i need to pk with 001


而把导电、导热都比较好的金属如金、银、铜、铁、锡、铝等称为导体。可以简单的把介于导体和绝缘体之间的材料称为半导体。在金属中，部分电子可以脱离原子核的束缚，而在金属内部自由移动，这种电子叫做自由电子。金属导电，靠的就是自由电子。

各种物体都能够传热，但是不同物质的传热本领不同．容易传热的物体叫做热的良导体，不容易传热的物体叫做热的不良导体。金属都是热的良导体。瓷、木头和竹子、皮革、水都是不良导体。金属中最善于传热的是银，其次是铜和铝．最不善于传热的是羊毛、羽毛、毛皮、棉花，石棉、软木和其他松软的物质。液体，除了水银外，都不善于传热，气体比液体更不善于传热

if ur question 3,銅傳熱最快,鋁電阻最低

Yes, at a given temperature, the thermal conductivity and electrical conductivity of metals are proportional. This is given by the Wiedemann-Franz Law. Refer to the following web-page for detailed explanation of the law:

http://hyperphysics.phy-astr.gsu.edu/Hbase/thermo/thercond.html

The reason is simple. Free electrons are responsible for conducting heat or electricity. Since metals have an abundance of free electrons, this is why metals are both good thermal conductors and electrical conductors as compared with non-metals.

Among the three metals you named, silver has the best thermal and electrical conductivity. This is followed by copper. Aluminium is not as good as copper.

You could find the respective thermal and eelcctrical conductivity values on the following two web-pages:

Thermal conductivity:

http://www.engineeringtoolbox.com/thermal-conductivity-metals-d_858.html

Electrical conductivity:

http://en.wikipedia.org/wiki/Electrical_conductivity