Clinical Thermometer: Understanding Its Working and Range For Class 7

A clinical thermometer is an important instrument used in our daily lives, especially in healthcare, to measure body temperature accurately. It helps in detecting fever and monitoring health conditions effectively.

Understanding how a clinical thermometer works and how to use it safely is essential for students and for everyday use. In this article, we will understand the structure, uses, precautions, and working of a clinical thermometer.

Table of Contents

• What is a Clinical Thermometer?
• Temperature Scale and Range
• Precautions for Using a Clinical Thermometer
• Why Mercury Does Not Fall in a Clinical Thermometer?

What is a Clinical Thermometer?

The thermometer that is used to measure the human body temperature is called a clinical thermometer. It is also called the doctor's thermometer.

It consists of a long, slender, and uniform glass tube with a bulb at one end containing mercury.

There is a small shining thread of mercury extending from the bulb in the thermometer. There is a kink near the bulb that prevents the mercury level from falling.

Temperature Scale and Range

The scale used to measure the temperature is known as the Celsius scale, denoted by °C, or the Fahrenheit scale, denoted by °F. It reads temperature from 35°C to 42°C or from 94°F to 108°F.

This is because the temperature of the human body varies only within this range. The average normal body temperature of a healthy human is 37 °C.

Precautions for Using a Clinical Thermometer

Precautions for using a clinical thermometer:

• The reading must be taken by keeping the level of mercury along the line of sight.
• Do not hold the thermometer by its bulb while reading it.
• The thermometer should be handled with care as it can break upon hitting a hard object, and mercury is a toxic substance.

Why Mercury Does Not Fall in a Clinical Thermometer?

Why does the temperature in a clinical thermometer not drop when it is taken out of the mouth?
When the thermometer is taken out of the mouth, the mercury in the bulb contracts as the temperature outside the body is normally less, and the mercury column breaks at the kink. Thus, the level of mercury remains constant even after taking the thermometer out of the mouth.

In this article, we understood what a clinical thermometer is and how it is used to measure human body temperature accurately. We also learned about its structure, the range of clinical thermometer, important precautions to follow while using it, and the reason why the mercury level remains constant after use.