Explain the Thermometers’ ?

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Explain the Thermometers’ ?..

Answer / km jyoti saini

These are the instruments used for measurement of temperature. These use mercury because it has following advantages as thermometric substance

I. It does not wet glass and does stick to it

II. It remains liquid over and wide range of temperature

III. It has a low specific heat and high conductivity

IV. Its expansion is approximately uniform, regular and large

V. It is opaque and therefore its level can be easily seen in the tube

VI. It can be obtained pure

VII. It treezes at -38.87oC and boils at 356oC and its upper limit can be raised to about 500oC by filling the top of tube with nitrogen under pressure

VIII. Its thermal capacity is very small

IX. It is a good conductor of heat

Clinical Thermometer:-It is used for taking the temperature of human body in Fahrenheit scale. It is designed to have a range of 64oc to110oC as the normal temperature of a body is 98.4oF. When the temperature rises, the mercury expands and in doing so forces its way through the construction and onto the tube . The column remains steady in the tube on cooling and thus maximum temperature can be ready easily

Maximum and minimum Thermometer(Six’s):-This thermometer is used for measuring maximum and minimum atmospheric temperatures. It consists of a circular bulb and a cylindrical bulb and are connected by a U-tube. Both the bulbs contain alcohol in cylindrical bulb expands and the expanding mercury pushes upward the index which remain undisturbed during fall of temperature. This gives maximum temperature. With a fall in temperature, alcohol contracts and mercury moves upward the 2nd index which gives minimum temperature