The thermomter is an instrument used for measuring temperature. The word thermomter is made up of the two words, ‘thermo’ meaning ‘heat’ and meter’ meaning ‘to measure’.
Thermomters usually have a liquid that expands when heated and contracts when cooled. Mercury is the most commonly used liquid and the mercury-in-glass type thermomter is the most common type of thermomter. Alcohol and ether are the other liquids commonly used in thermometers. Most thermometers are adjusted with the Fahrenheit or Celsius scale to measure temperature.
Galileo Galilei’s thermometer
Galileo Galilei’s thermomter is one of the earliest known thermometers. The thermomter had a water-filled glass bulb. The water moved up and down the bulb as the temperature
changed. Galileo called his thermomter the ‘thermoscope’.
The Celsius or the Centigrade scale is named after Anders Celsius. It was developed in 1742. scale, the freezing point of water is 0 cnthis boiling point of water is 100 °C O °C and the boiling point water is 100 C
The Fahrenheit scale was also developed in 1724 a German physicist, Gabriel Daniel Fahrenheit. In this scale, water freezes at 32 ℉ and water boils a 212 °F. The Fahrenheit scale was commonly used in English-speaking countries until the 1970s. Fahrenheit invented the alcohol thermomter in 1709 and the mercury thermometer in 1714.
The Kelvin scale is named after Lord Kelvin of Scotland, who developed it in the mid 1800s.
The Kelvin scale starts at 0. The zero point of this scale is equivalent to -273.16 “C, which is considered to be the lowest possible temperature in the universe. Therefore, the Kelvin scale is know also as the Absolute Temperature Scale. The temperature of the Kelvin scale reaches 275 at the 373°K at the freezing point of water an boiling point of water. The Kelvin scale is used by scientists.
Bulb thermomters are the most common type of thermometers. They are used for measuring body temperature. Most bulb thermomters use mercury as the indicator.
Bulb thermomters work on the principle that the volume of a liquid changes with
temperature. The liquid expands on increase in temperature. Medical thermometers are bulb thermomters. The tip of the thermomter is inserted in the mouth or the rectum
Bulb thermomter or placed under the armpit to measure the temperature
Digital thermometrs are the latest type of thermometers. Most doctors currently
recommend digital thermometers because they are more accurate than bulb thermomters. Moreover, nowadays are not very expensive. Digital thermomters can be used to measure the temperature of body by the rectal, oral, armpit, or ear canal routes.
Ear thermomters are also used to measure body temperature. The human eardrum is an accurate point to measure body temperature as it is located close to the hypothalamus
which is the body’s temperature regulator. The ear thermomter uses infrared radiation
to detect temperature.
Liquid crystal thermometer
Liquid crystal thermomters are plastic strip thermomters. They contain heat-sensitive liquid crystals in a plastic strip that change colour to indicate different temperatures. A
liquid crystal thermometer can be used to read body temperature by placing it against a
person’s forehead. Liquid crystal thermomters are safer than bulb (mercury-in-glass)
thermometrs, but are less accurate
An infrared thermomter measur temperature by detecting the infrared energy emitted by objects. Infrared thermometers are non-contact temperature measurement devices. These thermomters have a lens that helps the infrared (IR) energy to focus on to a detector. The energy is then converted to an electrical signal, which is displayed in units of temperature. While infrared thermomters are primarily used in industries, they are also useful at home for applications such as measuring the heating and cooling efficiency of a house.