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:

- Degree Centigrade or Degree Celsius – written as °C.
- Degree Fahrenheit - written as °F.
- 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.
- Add 32 to the answer obtained in step 2.

**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.

- 0°C
- 100°C
- 37°C

Q4) State True or False:

- 1°C = 273 K
- Water freezes at 100°C.
- 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.