Monday 22 September 2008

Thermometer

Thermometers are widely used for measuring temperature (hot or cold one).
There are 3 kind of thermometers, that is :
1. Liquid (normally mercury or alcohol) thermometer (commonly used)
Liquid thermometer contains liquid (not solid ar gas) inside it.
This liquid could be anything as long it has characteristics as follow :
  • Expand at hot condition and contract at cold condition.
  • Good expandibility, mean amongst other liquid it will expand or contract more.
  • Remain as liquid at working area of the thermometer, for example if we want to create a thermometer which will be used for measuring 0 - 100C, it means we must find liquid which has melting point below 0C and has boiling point over 100C
2. Thermocouple (for higher temperature, mostly used by industry)

3. Infra Red thermometer (must be placed at certain distance to keep its accurateness)


Everyone has different sense is saying hot or cold, for example if you stay in the air conditioned room, you will say outside the room is hotter, however for the person who live in a desert, he will say the same outside room (that you say hot) is colder than his place (at the desert).
To standarized the hot or cold feeling, people create scales that is:
  • Celcius scale

Celcius used water for scaling, he marked the temperature when water freezes at 0C and the temperature when water boils at 100C

  • Reamur scale

The same principle as Celcius however the temperature when water boil at 80C

  • Fahreinheit scale

Fahreinheit used brine and water for scaling, the temperature when brine freezes is marked at 0F and the temperature when water boils is market at 212F

  • Kelvin scale

Kelvin used water' absolute zero (mean there is no action at all of the molecule at that temperature) and continue to boil at 100K

  • etc

Generally we can say that the relation between Celcius scale, Reamur Scale and Fahreinhet scale can be compared as 5 : 4 : 9
And the relationship between Celcius Scale and Kelvin Scale is Celcius scale is 273 less then Kelvin scale
Why don't you try to figure their relationship by information above...
Good luck...

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