熱 電 偶 溫 度 計 問 題

热电偶温度计的工作原理：
两种不同的导体接触构成回路时，回路中将产生电势，这种电势的大小直接与两个接点之间的温度差有关，这种现象称为热电效应。

在古典电子理论中，热电势由温差电势和接触电势两部分构成。
温差电势是由均质导体的两端温度差引起的。接触电势是当两种不同的导体A与B接触时，因两者的自由电子密度不同，在接触点产生电子扩散，而形成的电势。接触电势不但是温度t的函数，其对热电势的贡献也远比温差电势大。因此，用兩種金屬造的熱電偶較一種金屬的靈敏度高。



用冰水原因是它的溫度是已知的 0 度C

2008-09-08 23:46:46 補充：
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http://zhidao.baidu.com/question/7768705.html

1.)為何要用2種不同的金屬

A voltage can still be developed when the two ends of a single piece of metal are maintained at different temperatures (this is the thermoelectric effect). But when you are going to measure the voltage, you need to connect an electric wire ( a second metal) to the two ends of the first metal. This is why thermocouple usually appears in two different metals.

若只用一種金屬
但在2種不同的溫度下
電壓不是也會不同嗎?

The voltages produced by a single piece of metal at various temperature differences are different.

2.)為何要利用冰水測量

The temperature of ice water provides a convenient reference point for the cold junction of the thermocouple. First, ice water is easy to produce and is cheap. Second, the temperature of ice water (ice co-exist with water) is rather stable at zero degree Celsius, which gives a suitable reference point for the thermocouple to operate.