Thermometer: Types, inventor, conversion, Functions and precautions to use

Thermometer: Types, inventor, conversion, Functions and precautions to use

Thermometer

What is Thermometer?

A device used for measuring the temperature of a body is called thermometer.

 Thermometer used for measuring the temperature of different materials and object.

 The two common scale  used for measuring temperature are Celsius and Fahrenheit scales.

Who invented the Thermometer?

In 1742 , a Swedish astronomer, Anders Celsius proposed a scale to be used for thermometer, which now bears his name.

 Thermometer was not created as a single invention. It was a step-by-step development. Some prominent development were made by Galileo Galilei Robert fludd and Santorio-Santorio.

How many types of scale of measuring the temperature?

There are three types of scales to measuring the temperature:-

 Celsius scale
 Fahrenheit scale
 Kelvin scale

Celsius scale --  most commonly used scale is the Celsius scale. According to this  scale the freezing point of water is taken at zero 0° C and the boiling point of water as 100°C.

 The reading taken in degree Celsius is written as °C in short,along with its numerical value.

Fahrenheit scale - the fahrenheit scale was devised by a German suggest Gabriel Fahrenheit in 1714. 
On this scale water boils at 212°F and freezes at 32°F.

Kelvin scale- Kelvin scale created by Lord Kelvin. The temperature on this scale is measured in kelvin(K).

According to this scale the freezing point of water is 273 Kelvin(K) and boiling point of water is 373 Kelvin(K).

 Therefore, by adding 273 any temperature can be converted from Celsius to Kelvin scale.

Conversion from One Scale to Another

The temperature scales are related to each other and can be converted from one school to another scale by using the following formula.

The relationship of the three scales is given as follows

°C/100 = °F-32/180 = K-273/100

To convert from degree Celsius to degree fahrenheit the simplified formulas is as follows

C/5=F-32/9

To convert from one scale to another scale we have
C=5/9*(F-32)  and.  F=9/5*(C+32)

For example,to  convert 20°C to degree Fahrenheit,we put the numbers in to the formula as
F=9/5*(C+32)
F=9/5*(20+32)
F=36+32=68°F
Therefore,20 degrre Celsius is ewual to 68 degree Fahrenheit.

How can you read a thermometer?

Before using a thermometer, let us learn how to read it. First of all, we find the temperature difference indicate between two  bigger marks.
 Now, we note down the number of division shown by smaller marks between them. for example, if  the qdifference between two bigger marks is 10 degree and there are 10 smaller division between them, then one small division will be read as 1 degree.
 You might have seen a doctor measuring the temperature of a sick person. the temperature of your body change when we fall sick.

What is Clinical thermometer?

Digital Thermometer

The thermometer used to measure the body temperature of human and animals is called clinical thermometer.

Who invented Clinical thermometer?

The clinical thermometer was invented by Sir Thomas Clifford Albert in 1866.

What is the Structure of a clinical thermometer?

A clinical thermometer is formed of a long and narrow glass tube with a bulb at its one end. This bulb is filled with Mercury. The glass tube encloses a thin capillary tube.

The capillary tube has a kink just a little above the bulb.Both scale,Celsius and Fahrenheit scale are shown on the thermometer.

The range of Celsius scale on the clinical thermometer is 35°C to 42°C and that of fahrenheit scale is 94° F to 108°F .

  How does use a clinical thermometer?

Before using a clinical thermometer first of all wash and dry the thermometer give it one or two jerks and make sure that the mercury in the capillary tube has fallen well below 35°C.  Put the bulb of the thermometer under the tongue for 1one minut. Take it out and read the temperatute

What is the normal temperature of human body?

The normal temperature of human body is 37° C or 98.6°F.

Precaution while using a clinical thermometer

 The following step must be followed while using a clinical thermometer:-

•  The thermometer must be washed with an antiseptic lotion like dettol or spirit or at least with clean water and dried with a clean dry cloth before and after every use. 
• Thermometer should be given to 3 soft jerk to bring the mercury in the capillary well below 35°C.
• Never hold the thermometer by the bulb.
• While giving jerkd care should be taken that the thermometer does not hit any object in the surroundings, otherwise its delicate bulb is likely to break. 
• While the thermometer is inside your mouth do not laugh or talk or yarn or not make any other action.This is to prevent the breakage of thermometer which may release Mercury into the mouth.
•  Mercury is poisonous and fatal once it gets into body it is difficult to remove it completely from the intenstine.
•  Note the reading in clear light The thermometer can be given small rotations to make the capillary and the level of mercury clearly visible. 
• Keep the level of mercury along the line of sight while reading the thermometer. 
• If the thermometer falls or breaks while giving jerks and the Mercury spills in the form of small droplets then take a small ball of kneaded wheat flour and roll it over the mercury droplet to pick them all. Put this contaminated wheat flour ball in a polythene bag, tie a knot tightly and hand it over to your nearest pharmacy to dispose it off.
• We should not use a clinical thermometer to measure the temperature of other object or take it close to a flame or keep in the sun all these activities may break it.

 What is Laboratory thermometer?

Laboratory Thermometer

 Laboratory thermometer is used to measure the temperature of various objects during experiments in a laboratory.

 What is the structure of a laboratory?thermometer

A laboratory thermometer consists of a very thin capillary tube of glass which is surrounded by thick and supportive glass walls.

The upper end of the capillary is closed after evacuation and the lower end is drawn in to a delicate bulb like shape,with a thin glass wall.

A laboratory thermometer is generally used to measure temperature ranging from  -10°C to 110°C. 

The stem of the thermometer has marks as horizontal lines to read a particular temperature. These mark are known as calibration.

Precautions while using a laboratory thermometer 

While the temperature is being taken, the bulb of the thermometer should be kept vertical and in contact with the object whose temperature is to be measured. It should not touch the bottom or the side of the container. 

The reading of temperature should be taken without removing the thermometer from its position.

The eye of the observer and the mercury in the capillary tube should be at same level.

Thermometer should not be used to measure temperature below its lower marking or above its highest marking.