Temperature

Temperature

Temperature is the degree of hotness or coldness of a body. The S.I unit of temperature is a kelvin (K).

(a) Thermometery.

A thermometer is an instrument which is used for measuring temperature on the basis of certain physical properties which change with changes in temperature.
These properties are called thermometric properties

Thermometric properties
A thermometric property is a property of a substance which continuously change with temperature and may be used for temperature measurements, these include:
-Increase in length.
-Change in potential difference
-Change in volume
-Change in pressure.

Thermometer scales.
There are 3 thermometer scales commonly used
(i) Celsius / centigrade scale (0C)
(ii) Fahrenheit scale (0F)
(iii) Kelvin scale/ absolute (k)

Relation between Celsius and Fahrenheit

image 258

And if Celsius scale reads 1000c then

image 259

Converting from Fahrenheit to Celsius.

image 260

Relationship between Celsius scale and Kelvin scale

image 261

Where C is temperature in Celsius scale and K is temperature in Kelvin scale.

Example

image 262

To obtain a standard scale on a thermometer. Two fixed points must be marked out on it. The upper and lower fixed points.