Physics question

Lower fixed point and upper fixed point are not characteristics of a temperature scale. They are only points that are chosen in the convenience of calibrating a thermometer.

As water is a most common substance that can be used all the time, thus its melting point and boiling point are chosen as two fixed points in drawing a thermometer calibration curve (remember that you need to have at least two points in order to draw a straight line graph).

You can ahere freely any temperature scale to the melting point and boiling point of water. In terms of the Celsius scale, they are 0 degree and 100 degrees respectively. In terms of the Fahrenheit scale, they are 32 degrees and 212 degrees respectivel. In terms of the Kelvin scale, they are 273 K and 373 K respectively.

You may, if you wish, use the melting point and boiling point of other substances as the two fixed points in calibrating a thermometer. But this is usually done in thermometers that are employed in measuring temperatures outside the range of our daily experiences, e.g. very low or very high temperatures encountered in industry or in scientific research.

你係唔係講緊water?
我可以同你講K唔係=F 上面既係錯
kelvin scale 係K
0C =273K

LOWER FIXED POINT: -273K
UPPER FIXED POINT: -173K
of water