Measurement of temperature is done by a particular property which is known as Thermometric property. “Thermometric property is defined as property which changes with the change in temperature.” Thermometric properties increase with an increase in temperature and decrease with a decrease in temperature. So TEMPERATURE α THERMOMETRIC PROPERTY.
For example: In our ordinary thermometer, we use mercury which rises or fall depends on temperature. So in the case of a mercury thermometer, length is thermometric property. Like this in constant volume thermometer, pressure is thermometric property. In resistance thermometers, resistance is thermometric property.
MESURMENT OF TEMPERATURE BEFORE 1954:
Before 1954, the temperature was measured by taking two references. One is the boiling point, and one is a freezing point.
Suppose there is temperature T1 at which thermometric property is X1 and for temperature T1 thermometric property is X1.
Now there is temperature T which is needed to be found. Now at this temperature thermometric property is X.
Now, we can write this T1α X1, T2α X2, Tα X.
Divide each equation by last one. So u will get
T1/T= X1/X & T2/T= X2/X
Subtract second equation from first equation
(T2 - T1)/ T = (X2 - X1)/ X
So if u know thermometric property at temperature T, then u can find Temperature below equation
T = X(T2 - T1) / (X2 - X1)
MEASUREMENT OF TEMPERATURE AFTER 1954:
After 1954, a temperature is measured by using only one reference point which is the triple point of water. Now suppose that it is Ti and at that point thermometric property is Xi.
Now u want to find temperature T, at which thermometric property is X.
so we can write this two equation, Tiα Xi, Tα X
Now divide second equation with first equation,
Ti/T= Xi/X .
U can write this equation like this, T = Ti.X / Xi
Here Ti represents the triple point of water, whose value is 273.15.
So put value of Ti in above equation,
T = (273.15)X / Xi
· Today we have different units to measure temperature like Celsius, Fran hit, Kelvin, Rankine, etc. let’s see the relation between them.
1. T(K)=T ( oC) + 273
2. T(F)=(9/5) T ( oC)+32
3. T(R)=(9/5) T(K)s
What is Thermometric Properties?
Reviewed by Crazy Kartoos
on
October 08, 2016
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