Scales of temperature:

A scale is marked on the thermometer. The temperature of the body in contact with the thermometer can be read on that scale. Three scales of temperature are in common in use. These are:

• Celsius scale or centigrade scale
• Fahrenheit scale
• Kelvin Scale

 

Celsius scale:

On the Celsius scale, the interval between lower and upper fixed points is divided into 100 equal parts. The lower fixed point is marked as 0°C and the upper fixed point is marked as 100°C.

 

Fahrenheit scale:

On the Fahrenheit scale, the interval between lower and upper fixed points is divided into 180 equal parts. The lower fixed point is marked as 32°F and the upper fixed point is marked as 212°F.

 

Kelvin scale:

In SI units, the unit of temperature is Kelvin (K) and its scale is called the Kelvin scale of temperature. The interval between lower and upper fixed points is divided into 100 equal parts. Thus, a change in 1°C is equal to a change of 1K. The lower fixed point on this scale corresponds to 273 K and the upper fixed point is referred to as 373 K. The zero on this scale is called the absolute zero and is equal to -273°C.

 

	°C	°F	K
Boiling point of water	100	212	373
Freezing point of water	0	32	273

 

DO YOU KNOW?

 

Sun’s core	15000000°C
Sun’s surface	6000°C
Electric lamp	2500°C
Gas lamp	1580°C
Boiling water	100°C
Human body	37°C
Freezing water	0°C
Ice in freezer	-18°C
Liquid in oxygen	-180°C