Thermometer
is a temperature measuring device that uses a variety of different
principles for measuring temperature. A thermometer has two important
elements, one is the temperature sensor and other is some means of changing
the measurement in to a value. For example, in mercury thermometers a bulb
is used as sensor and a scale determines the change in temperature. The word
thermometer is a combination of two smaller Greek words : 'Thermo' that
means heat and 'meter' that means to measure.
All types of thermometers fall in one of these two categories : Primary
Thermometers & Secondary Thermometers. Primary thermometers are those
thermometers for which some measurable physical property is related to
temperature in a way so that temperature can be calculated. Primary
thermometers usually don't require calibration. Secondary thermometers
possess a measurable property that changes with temperature. The secondary
thermometers have to be calibrated against a primary thermometer at least at
one temperature or at a number of fixed temperatures. Secondary thermometers
are more sensitive than primary ones, and are widely used because of their
convenience.
Types of Thermometers
Mercury Thermometer : Mercury thermometer consists of mercury in a
glass tube. It was invented by German physicist Daniel Gabriel Fahrenheit.
Mercury thermometer is also called “mercury-in-glass thermometer”.
Digital Thermometer : Digital thermometers are the best example of
the advancement of technology in the field of thermometers. Digital
thermometers are the new age temperature sensing devices.
Infrared Thermometers : Infrared thermometers are used to measure
the temperature using infrared radiations emitted from objects. They are
called non-contact thermometers due to the ability of the device to measure
the temperature from a distance.
Galileo Thermometer : Galileo thermometer is made of a sealed glass
cylinder containing a clear liquid. It is also known as thermoscope or
Galilean thermometer. It is named after Italian physicist Galileo Galilee.
Alcohol Thermometer : Alcohol thermometers are used for measuring
low temperatures. It is also known as spirit thermometer. Alcohol
thermometer is an alternative for mercury thermometer and works in a similar
way.
Invention of Thermometers
The first thermometer is thought to have been invented by a very famous
Italian scientist called Galileo Galilei in 1606. His first thermometer was
a very simple one. His thermometer was based on the idea that as things get
hot they expand and as they cool down they contract. At one end, the
Galileo's thermometer was open, which made it sensitive to air pressure
changes. However the first "closed" thermometer was invented in
1641 by Ferdinand II Grand Duke of Tuscany.
Selection of Thermometer
Now-a-days a number of thermometers are available in the market which are
based on different technologies. It's worthy to select a thermometer that is
easy to use and read. Accurate reading is confirmed from most types of
thermometers and the choice is often simply one's preference. We are giving
some points which will help you to purchase a good one :
- Cost : The cost of thermometer is very important. Different
thermometers have different pricing categories.
- Speed : You must know how much time the thermometer takes for
reading the temperature. So speed is an important factor to decide in
buying a thermometer.
- Comfort : The thermometer should have an easy interface so
that the reading can be done comfortably.
- Ease of use : You must know how to use the thermometer you
are buying.
