The thermometer is the highest thermometer, and the Guangdong and Hong Kong and Taiwan regions are called probes. It records the highest temperature that has been measured by this thermometer. After use, the thermometer should be "returned to the table", that is, the upper part of the thermometer is forced to slam down, so that the mercury that has been lifted into the tube can be returned to the glass bubble. Other thermometers must not be shaken, which is a major difference between thermometers and other liquid thermometers.
The thermometer is also called "medical thermometer". The working substance of the thermometer is mercury. Its glass bubble volume is much larger than the volume of the upper tube. Mercury in the bubble, due to the influence of body temperature, produces a slight change, and the expansion of the volume of mercury causes a significant change in the length of the mercury column in the tube. The temperature of the human body is generally between 35 ° C and 42 ° C, so the scale of the thermometer is usually 35 ° C to 42 ° C, and the range of each degree is divided into 10 parts, so the thermometer can be accurate to 1 / 10 degrees. The neck of the thermometer near the bubble is a very narrow curved neck. When the body temperature is measured, the mercury in the bubble expands by the heat volume, and the mercury can rise from the neck portion to a position inside the tube. When the body temperature reaches the thermal equilibrium, the mercury The column is constant. When the thermometer leaves the human body, the outside temperature is low, and the mercury shrinks in the cold volume, and is broken in the narrow curved neck portion, so that part of the mercury that has been lifted into the tube cannot be returned, and the mercury column is kept in contact with the human body. The height reached.
Because mercury mercury thermometer is a toxic element, it is gradually being replaced by an electronic thermometer. The electronic thermometer has the advantages of fast temperature measurement, digitization, not easy to break, automatic storage and record, etc., and is gradually entering the home of the public.