Whenever you are ill, your doctor or your parents talk about body temperature. You must have experienced that during fever, the body temperature rises and the doctor measures your fever with a device name thermometer. In this blog, we will learn about it. and also about the temperature. Temperature is a reliable measure of the hotness of an object.

 

In your day-to-day life, you come across a number of objects. Some of them are hot while some are cold. How do you decide which object is hotter than the other? We often do it by touching, but many times the method of touching is not reliable.

 

Let�s do an activity.

 

Take three mugs. Label them as X, Y, and Z. Put cold water in mug� X� and hot water in mug �Y�. Mix some cold and hot water in mug �Z�. Now dip your left hand in mug �X� and right hand in Mug �Y�. After keeping both hands for 2-3 minutes in mugs X and Y respectively, put both the hands simultaneously in mug �Z�. You will be surprised to find that both hands do not feel the same.

 

The sense of touch gives you just an approximate measure of temperature. Temperature is measured by a device called a Thermometer. It is used to measure the temperature of a body accurately.

 

Types of Thermometers

 

There are various types of thermometers but the most widely used is the �Clinical Thermometer.� It is used for measuring the temperature of the human body. It is used in homes as well as in clinics.

 

You must have seen Laboratory Thermometer in your school lab. It is used in schools and other laboratories for scientific research and is also used in industries. It is much larger than Clinical Thermometer and can measure much higher temperature.

 

Structure of Clinical Thermometer

 

A clinical Thermometer is used to measure the temperature of the human body. Let us understand its structure. It consists of a long glass tube that is attached to a smaller tube. The long narrow uniform glass tube is called the �Stem� of the thermometer. The smaller tube which contains mercury is called the �Bulb�. Outside the bulb, a small shining thread of mercury is seen. If you do not see the mercury thread, rotate the thermometer a bit till you see it.

 

Closely observe the region where the stem meets the bulb. The mercury thread appears bent. This is called a kink. Actually, all clinical thermometers have a kink that prevents the mercury to fall down rapidly so that temperature can be recorded conveniently. Imagine, what will happen if the mercury falls down as soon as the doctor takes the thermometer out of your mouth.

 

The doctor would never be able to record the temperature properly. That�s why a kink is very useful. You will also find a scale on the thermometer. The scale is present on both sides of the stem. The temperature on one side of the scale is measured in degree �Celsius� & denoted by the symbol degree capital C.

 

While the temperature on the other side of the scale is measured in Fahrenheit & is denoted by the symbol degree capital F. Thus a clinical thermometer indicates the temperatures in the range of 35 degree Celsius to 42 degree Celsius on the Celsius scale and 94 degrees Fahrenheit to 108 degrees Fahrenheit on the Fahrenheit scale.

 

The normal temperature of the human body is 37 degrees Celsius but can be slightly higher or lower varying from person to person. You should know that India has adopted the Celsius scale.

 

Galileo invented the thermometer and named it �Thermo scope�. Remember not to use a clinical thermometer for measuring the temperature of any object other than the human body. Also, avoid keeping it in the sun or near a flame. It may break.

 

Structure of Laboratory Thermometer

 

The thermometer which is used to measure the temperature of objects other than the human body is known as Laboratory Thermometer. It also contains mercury which expands to indicate the temperature. It has only Celsius ranging from -10 degrees Celsius to 110 degrees Celsius.

 

Let's analyze its structure. Like the �Clinical Thermometer,� it also possesses a long glass tube connected to a Bulb filled with mercury. Have you noticed that the stem & bulb of a laboratory thermometer are longer as compared to a Clinical Thermometer?

 

Let's do an activity to understand the functioning of the laboratory thermometer.

 

Take some warm water in a beaker. Dip the thermometer in water so that the bulb is immersed in water but does not touch the bottom or the sides of the container. Hold it vertically. Observe & wait till the mercury thread becomes steady. This is the temperature of water at that time.

 

Other types of thermometers are:

 

1. Infrared - It is also called a black body radiation thermometer.
2. Galileo - It is named after Italian physicist �Galileo Galilee�.
3. Digital remote - It is intended for precision centigrade temperature measurement.