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| Scales of Temperature |
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| A reference scale with respect to which the temperatures can be measured is known as 'scale of temperature'. Various scales of temperatures are in use. Important scales of temperature are: |
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 Celsius scale |
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 Fahrenheit scale |
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 Kelvin Scale |
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| To devise a scale of temperature, fixed reference points (temperature) are required, with respect to which all other temperatures are measured. For both Celsius and Fahrenheit Scales of temperatures, the fixed points are as follows: |
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| Lower fixed point: Melting point
of pure ice at normal atmospheric pressure is regarded as the lower fixed
point. |
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| Upper fixed point: Boiling point
of pure water at normal atmospheric pressure is regarded as the lower fixed
point. |
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| Celsius scale of temperature was devised by a Swedish astronomer Anders Celsius (1701-1744). In this scale, the lower fixed point (the temperature of melting ice at normal atmospheric pressure) is taken as zero degree Celsius, written as 00C. The upper fixed point (the temperature of pure boiling water at normal pressure of 76 cm of mercury) is considered to be hundred degree Celsius, written as 100OC. The interval between 00C and 1000C is divided into hundred equal parts. Each part represents 10C. This is a convenient scale of temperature, which is widely used. |
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| Celsius Scale of Temperature |
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| This scale of temperature was devised by Gabriel Fahrenheit (1687-1736). The lower and upper fixed points in this scale are considered as 320F and 2120F respectively. The interval of 1800 F is divided into 180 equal parts. Each part is known as 10F. This is widely used by doctors. |
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| Fahrenheit Scale of Temperature |
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| Relation between Celsius and Fahrenheit scales of temperature: |
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| 1000C = 1800F |
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| Relation between Celsius and Fahrenheit scales of temperature |
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| In the figure, AO represents temperature C. On Celsius scale and O'B represents the same temperature on Fahrenheit scale. Let us see how we can relate them. |
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| Let AO = C divisions = C0 C. |
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| But ice point on Fahrenheit scale corresponds to 320F. |
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| For example: |
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| 1) Convert 200C into Fahrenheit scale |
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| (2) Convert 850C into Fahrenheit Scale. |
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| Similarly, to represent temperature on Fahrenheit Scale into Celsius Scale: |
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| Examples: |
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| 1. Represent 590 F on Celsius Scale. |
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 590 F=150 C |
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| 2. Represent 770 F on Celsius Scale. |
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 770 F=250 C |
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