Temperature and its measurement Science class 6 Question Answer 

Temperature is an important part of our daily life. We often say that the day is “hot” or “cold,” but how do we know the exact degree of hotness or coldness? This is where temperature comes in. Temperature tells us how hot or cold an object or place is. It helps us understand weather changes, body health, and many scientific processes. To measure temperature accurately, we use instruments like thermometers. 

In this chapter, we will learn 

 1- what temperature is                                                                       2- how it is measured                                                                         3- the different types of thermometers,                                          4- why it is important in science and daily life.

Temperature and its measurement Science class 6 Question Answer

What is Temperature?

Ans:- Temperature is a physical quantity that tells us how hot or cold an object is. It helps to compare the hotness or coldness between two bodies. It also tells us the degree of hotness or coldness of a body. The sensation of hot and cold depends on the flow of heat energy: 

Heat flows from a body at higher temperature to a body at lower temperature, until both acquired same temperature.

Example: When you touch a hot cup of tea, heat flows from the cup to your hand.

Units of Temperature

Just as length is measured in meters and weight in kilograms, temperature also has units.
The commonly used units of temperature are:

1- Degree Celsius (°C) – used in most countries and in laboratories.

2- Fahrenheit (°F) – used mainly in the USA.

3- Kelvin (K) – SI unit of temperature, used in scientific studies.

Important Points

Ice melts at 0°C or 32°F

Water boils at 100°C or 212°F

Kelvin scale starts at absolute zero , 0 K = –273°C

Relation between Celsius, Fahrenheit, and Kelvin

Temperature can be measured in three common scales: Celsius (°C), Fahrenheit (°F), and Kelvin (K).
These scales are related to each other by simple formulas:

1. Celsius and Fahrenheit:

$$°F = \left(\frac{9}{5} \times °C\right) + 32$$
$$°C = \frac{5}{9}(°F - 32)$$

2. Celsius and Kelvin:

$$K = °C + 273$$
$$°C = K - 273$$

3. Fahrenheit and Kelvin (using Celsius as link):

$$K = \frac{5}{9}(°F - 32) + 273$$

What is Thermometer?

Ans:- A thermometer is an instrument used to measure temperature of a living body or object. A thermometer has a scale marked on it for reading temperature. The most common temperature  scale marked on the thermometer for measuring temperature is the 'celsius scale'.

How many types of thermometer? Name them.

Ans:- There are two types of thermometer.

1- clinical thermometer

2- laboratory thermometer

What is clinical thermometer?

A clinical thermometer is a special type of thermometer that is used to measure the temperature of the human body.

Write five features of clinical thermometer.

Ans:- The five features of clinical thermometer are

1- The range of clinical thermometer is  Usually from 35°C to 42°C or 94°F to 108°F, since this is the range of human body temperature.

2- It has a narrow glass tube filled with mercury or sometimes alcohol in modern versions.

3- It has a small kink in the tube near the bulb that prevents the mercury from falling back quickly, so the temperature can be read easily after removing it from the body.

4- It is marked with a clear scale in Celsius (°C) or Fahrenheit (°F) for accurate temperature reading.

5- It has a bulb at one end filled with mercury or colored alcohol.

How to use clinical thermometer to measure body temperatur

We can use a clinical thermometer to measure the body temperature of a patient as follow:

1-  Wash the thermometer properly. If antiseptic solution is not available, wash it with clean water.

2- Hold the thermometer tube firmly in your hand and give it a few jerks so that the mercury thread in the thermometer tube falls below the reading of 35 °C. Never hold a thermometer by its bulb.

3- Place the thermometer bulb of the under the patient's tongue or armpit and gently hold the thermometer tube. Keep the thermometer bulb in the  mouth or armpit of a  patients for about one minute, then remove the thermometer.

4- To read the temperature, hold the thermometer horizontally in your hand and rotate it slowly. A position will come when you will see a magnified image of  the mercury thread in the tube. Read the temperature on the thermometer tube in level with the top of the mercury thread. This will give the body temperature of the patient.

Precautions should be taken to using a clinical thermometer 

1- the clinical thermometer should be washed before and after each use, preferably with an antiseptic solution.

2- Before using the clinical thermometer, ensure that the mercury level in the tube is below 35 °C mark.

3- Read the clinical thermometer with the mercury level aligned with your sight.

4- Do not hold clinical thermometer by the bulb while reading it, as this may cause the bulb to break.

5- Handle the clinical thermometer with care as it can break if it strikes a hard object.

How does a clinical thermometer work

A clinical thermometer measures body temperature by utilizing the principal of thermal expansion. When the thermometer 's bulb is placed in the patient's  mouth or armpit, then some of the body heat of  patient  is transferred to the mercury in the thermometer bulb. This heat causes the mercury inside the thermometer to expand  due to which the mercury thread is pushed to a higher level in the thermometer tube. The higher  the  fever of a patient, greater will be his body heat and hence higher will be the level of  mercury or higher will be the temperature shown by the thermometer.

What is laboratory thermometer?

A laboratory thermometer is a type of thermometer that is used in laboratories to measure the temperature of different substances like liquids, solutions, or solids during experiments. 

It is an instrument used to measure temperatures accurately in scientific experiments, usually ranging from –10°C to 110°C or sometimes higher.

Features of Laboratory Thermometer.

1-  It is usually made of glass.

2- Mercury or coloured alcohol is used as the liquid inside the thermometer which expands or contracts with temperature changes.

3- The entire length of thermometer glass tube is calibrated in degree celsius but sometimes degree fahrenheit.

4- the graduationsmarked on the tube of a commonly used laboratory thermometer range from -10 °C to 110 °C 

Precaution that be taken while using Laboratory Thermometer

1- laboratory thermometer keeps vertically (or upright) while measuring temperature.

2-Ensure the thermometer bulb is completely surrounded by the substance whose temperature is to be measured.

3- Avoid allowing the thermometer bulb to touch the sides or bottom of the container in which the substance is place

4- Read the thermometer while its bulb is still in contact with the substance whose temperture is being measured.

5- Read the thermometer with the mercury level aligned with your line of sight.

6- Do not hold the thermometer by the bulb.

7- Handle the thermometer carefully, as it can break if struck against a hard surface.

Differences between clinical thermometer and laboratory thermometer

1- The clinical thermometer has a very short temperature range that is 35°C to 42°C but laboratory thermometer has large temperature range that is –10°C to 110°C

2-  The clinical thermometer has a kink in its tube which prevent the backflow of mercury into the bulb but laboratory thermometer has no kink.

3- The clinical thermometer measures temperature more accurately up to 0.1 °C but laboratory thermometer measures temperature less accurately than clinical thermometer up to 1 °C

Maximum and minimum thermometer 

The thermometer which automatically records the maximum and minimum temperature of a day is called maximum and minimum thermometer.

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