What is Temperature? In our everyday life we all listen to a statement “Today the temperature is 23 degree Celsius or 23°C or some other value". Now have you ever asked yourself a question what exactly does temperature means? Let us understand it. • The intensity of the heat present in any body is known as temperature.

• It is measured using an instrument called Thermometer.
• The unit in which it is measured is Degree Celsius(°C) and the standard unit is Kelvin.(K)

Units and Conversions

There different units to measure the temperature and are listed below:

1. Degree Centigrade or Degree Celsius – written as °C.
2. Degree Fahrenheit - written as °F.
3. Kelvin- written as K.

Kelvin is considered as the SI unit of temperature.

Formula:

 Temperature in degree Celsius = 273 - Temperature in Kelvin

Example 1: Convert 23°C into Kelvin.

Solution: 1°C = 273- Temperature in K

Therefore 1 Kelvin = 273 – 1°C = 272 K.

Conversion from Degree Celsius to Fahrenheit:

The conversion can be done in following 3 steps:

• Multiply the temperature in degree with 9.
• Divide the answer by 5.

Example 2: Convert 23°C to °F.

Solution: Following the above 3 steps one by one we get,

(23 x 9) = 207 and then

(207 ÷ 5) = 41.4 and then

41.4 + 32 = 71.4°F. From this figure we can learn two things:

• As the reading of thermometer increases the value of heat increases and hence the body becomes more hot.
• As the reading of thermometer decreases the value of heat decreases and hence the body becomes more cold. Points to Remember

• The normal temperature of a human body is 37 degree Celsius. • The Celsius is marked from 0°C to 100°C.
• The Fahrenheit scale is marked from 32°F to 212°F.
• The thermometer used for the medical purpose has a special name Clinical Thermometer.

Practice Question

Q1) What is the normal temperature of a human body?

Q2) At which temperature water starts to boil?

Q3) Convert the following to Degree Fahrenheit.

1. 0°C
2. 100°C
3. 37°C

Q4) State True or False:

1. 1°C = 273 K
2. Water freezes at 100°C.
3. Temperature of ice is 0°C.

Recap

• Thermometer is used to measure temperature of any body.
• Unit of temperature can be K or °C or °F.
• Temperature in °C = 273 – Temperature in K.
• 0°C = 32°F.
• Temperature of ice is 0°C or 32°F.
• Doctors use Clinical Thermometer to measure temperature of patients.