Physics (thermometer~urgent)

2010-06-18 1:41 am

Resistance thermometer運作原理:
利用金屬物料因為越高溫度而會有越大電阻既特性。溫度愈高，電阻愈大，電流愈細，由此可以測量溫度。

Thermocouple thermometer運作原理:
由兩種金屬線連結成電路。係兩個接駁位，一個放係已知既參考溫度中，通常係冰點，另一個就放係要測溫既野度。如果兩端溫度唔同就會產生電流，而兩端溫度差別會同電流大細成正比。

以上不是自相矛盾嗎?
越高溫度,,越大電阻,,電流愈細
又點會"兩端溫度差別會同電流大細成正比"???

thanks~~

回答 (1)

天同

2010-06-18 4:07 am

✔ 最佳答案

The two types of thermometers work on different principles. A thermocouple thermometer works on the principle of Seebeck effect. When two dissimilar metals are joint together, the junction producea an emf (electromtive force) when it is heated. The higher the temperature of the junction, the larger the is the emf produced. Hence, a thermocouple thermometer makes use of the junction emf to measure temperature.

A resistance thermometer, however, works on the (electrical) resistant property of materials. For most materials, higher temperature causes high resistance. This material property is used to measure temperature.

You may refer to the following web-page for a short description of thermocouple ther mometer.

http://www.tpub.com/content/armymunitions/mm0483/mm04830010.htm

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