Introduction to Thermometer
We can measure temperature using an instrument called a thermometer. A sealed tube with markings on it makes up an analogue thermometer. Temperatures are indicated with these markers in either Celsius or Fahrenheit. A clinical thermometer has different markings than a weather thermometer, although they both function the same.
In addition, the current thermometer was innovated in 1709 by Daniel Fahrenheit. It was a tube surrounded by glass that had a numerical scale, called the Fahrenheit scale. The first clinical thermometer was made by Sir Thomas Allbutt, an English medical practitioner. In this article we will discuss the thermometer in detail.
What is a Thermometer?
The term thermometer comes from the Latin word ‘Thermo’ which means hotness and ‘Metrum’ which means estimate. Thus, a thermometer is a knowledge-based tool for estimating temperature. The temperature of a device or material makes reference to how cold or hot it is. The human body comes in contact with the thermometer on a daily basis.
You can use this thermometer when you want to know how cold or hot it is outside. A physician takes your body temperature when you have a doctor’s meeting. A thermometer accommodates two important components: a sensor and a device. A thermometer works by using the physical properties of various materials. For example:- liquid, solid, and gas.
Measuring the Temperature of Different Phases
Types of Thermometer
There are different types of thermometers used to calculate the temperature. Some of them are:-
Objective thermometer
Nursing thermometer
Analog thermometer
Infrared clinical thermometer
Mercury-in-glass clinical thermometer
Spirit thermometer
Fixed pressure gas thermometer
Certain volume thermometer
Radiation pyrometer thermometer
Dry bulb thermometer
Thermometer for Liquids
What’s Inside a Thermometer?
Liquid thermometers frequently include both Celsius temperature and Fahrenheit temperature scales, which are shown on either side of the tube. The highest thermometer is a closed type of liquid thermometer. In the highest thermometer, the liquid is moved up the glass tube, but cannot come down easily when the temperature moves down.
Several thermometers are made for utilising liquids. The mercury thermometer was the first, originated by Daniel Fahrenheit. A mercury-in-glass thermometer contains liquid mercury in a glass bulb devoted to a thin, surrounded tube. As the temperature increases, the mercury becomes larger. Afterward, mercury is extremely poisonous. It is simple and not expensive.
A Mercury Thermometer
Uses of Thermometer
It is used to notice if you are suffering from fever.
It is used to see how cold or hot it is outside.
It is used in schools, hospitals, houses, automobiles, industries, etc.
It is used to measure the temperature of babies also.
It is used to track and record the opposites of temperature at a place.
It is used to estimate the maximum and minimum air temperature like in a greenhouse.
It is used for measuring the temperature during physical exams.
It is used for measuring the temperature of a pool.
Thermometers Facts
The thermometer is a straightforward device that is used to calculate the temperature.
People are allowed to tell how cold and hot it is by knowing the temperature measurements.
A remarkable temperature substitute usually shows something is wrong.
Thermometers have been in all directions for a number of centuries.
A thermometer includes many elements like a tube, bulb, and stem.
The tube doesn’t survive an automated thermometer.
The very first thermometer that originated contained water in them alternately mercury.
The difference between a thermometer and a thermoscope is that a thermometer has a valuation while a thermoscope does not have any valuation.
The Galileo thermometer was innovated in 1593.
The Celsius scale has 100 temperatures and Fahrenheit has 180 temperatures.
Summary
In this article, it was discussed how the thermometer is used nowadays and also studied the definition of the thermometer, uses of the thermometer, types of thermometers, and facts about thermometers.We can measure temperature using an instrument called a thermometer. A sealed tube with markings on it makes up an analogue thermometer. Temperatures are indicated with these markers in either Celsius or Fahrenheit. A clinical thermometer has different markings than a weather thermometer, although they both function the same.
FAQs on What is Thermometer ?
1. What is a thermometer and on what principle does it work?
A thermometer is a scientific instrument used to measure temperature or a temperature gradient. The working principle of most common thermometers is based on the thermal expansion of substances. When a substance gets hotter, it expands, and when it gets cooler, it contracts. This change is calibrated on a scale to indicate the temperature.
2. What are the two main types of thermometers and their primary uses?
The two main types of thermometers discussed in the CBSE syllabus are:
- Clinical Thermometer: Used to measure human body temperature. It has a specific range, typically from 35°C to 42°C.
- Laboratory Thermometer: Used in science labs for experiments. It has a much wider range, often from -10°C to 110°C, to measure the temperature of various substances.
3. What is the main difference between a clinical thermometer and a laboratory thermometer?
The key difference lies in their design and purpose. A clinical thermometer has a small constriction or 'kink' in the tube just above the bulb. This kink prevents the mercury (or galinstan) level from falling back on its own, allowing time to take an accurate reading after removing it from the body. A laboratory thermometer does not have this kink, as it is designed to show the current temperature of a substance it is in direct contact with.
4. Why was mercury traditionally the preferred liquid in most thermometers?
Mercury was widely used in thermometers due to its several useful properties:
- It is a silvery-grey liquid metal, making it easy to see inside the glass tube.
- It expands and contracts uniformly with temperature changes.
- It has a very high boiling point and a low freezing point, allowing it to measure a wide range of temperatures.
- It does not stick to the sides of the glass tube, ensuring accurate readings.
However, due to its toxicity, mercury is now largely replaced by alcohol or digital sensors.
5. How does a modern digital thermometer work without using any liquid?
A modern digital thermometer uses an electronic sensor called a thermistor located at its tip. The thermistor's electrical resistance changes precisely with temperature. An internal microchip measures this resistance, converts it into a temperature reading, and displays it on a small LCD screen. This method is fast, safe, and does not involve any hazardous materials like mercury.
6. What are the correct steps to measure body temperature with a clinical thermometer?
To measure body temperature accurately, first, wash the thermometer with an antiseptic solution. Hold it firmly and give it a few jerks to bring the liquid level below 35°C. Then, place the bulb of the thermometer under your tongue for about one to two minutes. After the time is up, take the thermometer out and read the temperature by keeping the level of the liquid along your line of sight.
7. What important precautions must be taken while using a laboratory thermometer?
When using a laboratory thermometer for an experiment, you should follow these precautions:
- The thermometer should be held vertically and not tilted.
- The bulb should be fully surrounded by the substance whose temperature is being measured.
- The bulb should not touch the bottom or the sides of the container.
- The reading should be taken while the bulb is still in the substance, by keeping your eye level with the top of the liquid in the capillary tube.
8. How can you perform a simple check to see if a thermometer is accurate?
You can check a thermometer's accuracy using the known freezing point of water. Fill a glass with crushed ice and add a little cold water. Stir it and let it sit for a couple of minutes. Place the thermometer's bulb in the ice water, ensuring it doesn't touch the glass. An accurate thermometer should read 0°C or 32°F. If it shows a different reading, it may need to be calibrated or replaced.
