What is Thermometer? How Does It Work and What Types?

What is a Thermometer? How does it work? Thermometer Types

The thermometer is a tool for measuring temperature and there are various thermometers. In this article we will give information about the subject of thermometer. Good readings

What is a thermometer

The instrument for measuring temperature is called a thermometer . Another name for thermometers is temperature meter . The termometer dates back to ancient Greece as a word origin and was formed by the combination of the words thermos (temperature) and metron (measure).

How the Thermometer Works

Usually when the temperature of an environment or substance is measured, this thermometer or The environment interacts. There is a heat exchange between the thermometer and the materials with different temperature values. In this way, the temperature of the substance or the medium passes to the thermometer, creating a number of physical changes.

What are the physical changes that can be observed on the thermometer?

The physical changes that can be observed on the thermometer are as follows:

Solid, liquid or gas – expansion
Differences in gases – pressure
Solids – resistance and changes in color.

How to Measure a Patient's Body Temperature

In order to measure the body temperature of people with a febrile illness, the thermometer is brought into contact with the patient's body, so that there is a heat flow from the body with high fever to the thermometer. The thermometer takes this heat and transfers it to the red liquid in its chamber and the liquid that sees this heat starts to expand. The higher the body temperature, the longer the expansion, the longer the liquid and the thermometer between the expansion of the thermal equilibrium occurs when the expansion ends. With the end of the expansion, it is possible to say that the value of the body temperature is the value of this liquid. That is, when this fluid remains constant at some point, the patient's temperature is equal to that value.

What are the types of thermometers?

Thermometers can also vary according to the substance or environment whose temperature is desired to be measured. In this case, the thermometers must be selected for their intended use. In general, thermometers can be divided into three as follows:

Liquid Thermometers
Metal (solid) thermometers
Gas Thermometers

Information on Liquid Thermometers

Such thermometers; The capillary glass tube consists of three parts, colored liquid and reservoir . A liquid thermometer can also be used as a liquid colored color of mercury, alcohol or spirit . The most preferred one of these is the element mercury

There are some sensitivities in the temperature measurements made with liquid thermometers. These are

Stenosis of capillary tubes
Use of liquids with high expansion coefficients
Large fluid reservoir
It depends on the excess of the temperature range, ie the number of compartments.

Here it is necessary to clarify the concept of absolute temperature

What is the concept of absolute temperature?

Absolute temperature ; it is the theoretical temperature in which a substance stops atoms and molecules, that is, there is no movement and hence the kinetic energy is assumed to be zero. The value of this temperature is also Kelvin or -273,16 ° C.

The temperatures of substances found in nature can never be lower than the absolute temperature. When substances are above the absolute temperature, their atoms and molecules are always mobile. These moving atoms and molecules collide during their movements and transfer their energies to each other.

How much liquid thermometers are divided into?

Liquid thermometers;
Patient thermometer (temperature measuring range 33 to 42 ° C)
Wall thermometer (temperature measuring range 30 to 50 ° C)
Laboratory thermometer (temperature measuring range -10 to 110 ° C) can be divided into three.

As mentioned above, liquid thermometers use mercury, alcohol or spirit .

Why is mercury used in liquid thermometers?

The expansion coefficient of mercury is lower than other liquids. Therefore, the increase will be high even if it grows very little in volume. With mercury thermometers it is possible to measure temperatures between -39 and 357.

Why use alcohol in liquid thermometers?

The degree of freezing of alcohols is very low. Mercury cannot measure a temperature of less than -39 degrees, but with an alcoholic thermometer it is even possible to measure – 115 degrees. Therefore, an alcoholic thermometer is used when winter is very cold. Alcoholic thermometers are also used when measuring the freezing temperatures of the poles.

Information on Metal Thermometers

Metal thermometers are often used to measure very high temperatures. Particularly in industry, temperatures are measured by means of metal thermometers. These thermometers are generally used to measure the temperatures of the furnace and therefore the degree settings of the furnaces such as melting, cooking or drying are made. The development of metal thermometers also depends on the expansion properties of metals.

Information on Gas Thermometers

The most responsive to temperature changes with respect to solids or liquids are gases. Gas thermometers are especially used in areas where precise measurements are made. Gas thermometers are especially used in laboratory environments. The operating principle of a gas thermometer depends on the expansion of the gases.

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