Temperature

What is Temperature?

Temperature refers to the hotness or coldness of a body. Temperature is represented by the letter ‘T’.

Temperature is a way to tell if something is hot or cold. When an object feels warm, we say it is hot, and when it feels cool, we say it is cold. So, we prefer hot tea or coffee in the winter and cold drinks in the summer.

Objects that feel very warm are called hot objects. Hot objects have higher temperatures. Some examples of hot objects include sun, fire, tea, coffee, etc.

Objects that feel cool are called cold objects. Cold objects have lower temperatures. Some examples of cold objects include ice, ice creams, cold drinks, snow, etc.

Temperature Measurement Units

The Units of temperature are as follows:

Celsius (°C)

Fahrenheit (°F)

Kelvin (K).

We use the degree symbol (°) in the measurement of temperature to denote degrees on various temperature scales like Celsius (°C) and Fahrenheit (°F) scales.

Example: If the temperature in the afternoon is 104°F, the temperature in the evening is 95°F and the temperature at night is 59°F, what is the temperature difference in the afternoon and at night?

a) 35°F
b) 45°F
c) 53°F
d) 163°F

Answer: b) 45°F

Explanation: Temperature difference in the afternoon and at night = 104 − 59
= 45°F

Temperature Measuring Devices

We use a thermometer to measure the temperature of an object.

Reading a Thermometer

The rise and fall in the level of liquid mercury (red-marked) shows the rise and fall of temperature. 

• The boiling point of water is 100°C which is marked on the thermometer. It is read as hundred degrees Celsius (100°C ).

• The freezing point of ice is 0°C, which is marked on the below thermometer. It is read as zero degrees Celsius (0°C ).

Example: What temperature is shown below on the thermometer?

a) 20 K
b) 20 °F
c) 20 °C
d) 20 °K

Answer: c) 20 °C 

Explanation: The temperature shown on the thermometer is 20°C. It is read as 20 degrees Celsius.