List the thermometers commonly used in daily life and talk about their uses?

There are many types of thermometers, generally divided into the following categories:

1. Liquid crystal thermometer: Liquid crystals made with different formulas have different phase transition temperatures. When the liquid crystal is exposed, its optical properties will also change, making the liquid crystal look discolored. If liquid crystals with different phase transition temperatures are painted on a piece of paper, the temperature can be known from the change in color of the liquid crystal. The advantage of this thermometer is that it is easy to read, but the disadvantage is that it is not accurate enough. It is often used in ornamental fish tanks to indicate water temperature.

2. Resistance thermometer: The resistance of metal will increase as the temperature increases. When the temperature changes little, the resistance of the anemometer has an approximately linear relationship with the temperature. In a larger temperature range, usually It can be represented by a simple quadratic polynomial. By measuring the resistance of a metal, you can know what its temperature is. This kind of thermometer is usually made of platinum wire, can be accurate to 10-3 degrees Celsius, and is often used for precise measurements. Due to the high melting point of platinum, the measurable temperature range is wider, about -250°C to 1200°C.

3. Gas thermometer: Under fixed pressure, the volume of gas with low density has a linear relationship with temperature. A thermometer made using this relationship is called a constant pressure gas thermometer. At a fixed volume, the pressure of a gas with low density has a linear relationship with temperature. A thermometer made using this relationship is called a constant volume gas thermometer.

4. Rotary thermometer: The rotary thermometer is made of a curled bimetallic sheet. One end of the bimetal piece is fixed, and the other end is connected to the pointer. Due to the different expansion degrees of the two metal sheets, the bimetallic sheet curls to different degrees at different temperatures, and the pointer points to different positions on the dial. The temperature can be known from the reading on the dial.

5. Semiconductor thermometer: The resistance change of semiconductors is different from that of metals. When the temperature rises, its resistance decreases, and the change range is larger. Therefore, a small amount of temperature change can also cause significant changes in resistance. The resulting thermometer has high precision and is often called a thermometer.

6. Thermocouple thermometer: A thermocouple thermometer is composed of two different metals connected to a sensitive voltmeter. Metal contacts will produce different potential differences at both ends of the metal at different temperatures. The potential difference is very small, so a sensitive voltmeter is required to measure it. You can know the temperature from the voltmeter reading.

7. Optical pyrometer: If the temperature of an object is high enough to emit a large amount of visible light, the amount of thermal radiation can be measured to determine its temperature. This type of thermometer is a photothermometer. This thermometer is mainly made of a telescope equipped with a red filter and a set of circuits with a small light bulb, a galvanometer and a variable resistor. Before use, first establish the relationship between the temperature corresponding to different brightness of the filament and the reading on the ammeter. When in use, align the telescope with the object to be measured and adjust the resistance so that the brightness of the bulb is the same as that of the object to be measured. At this time, the temperature of the object to be measured can be read from the galvanometer.

In addition, there are metal sheath thermometers, marine thermometers, V-type thermometers, copper sheath thermometers and other thermometers