What are the principles of thermometer, hydrometer, dynamometer and sundial?

Thermometer: The traditional thermometer is based on the volume change of liquid at different temperatures (thermal expansion and cold contraction). The earliest thermometer was invented by Italian scientist Galileo (1564 ~ 1642) in 1593. Galileo made the first temperature detector in 1593 or 1603, trying to turn the uncertain hot and cold feeling into an objective expression of the thermal state of an object. This is an open tube connected to a glass ball container. Preheat the glass ball or add some water, and then pour it into the water. The rising height of water in the tube changes with the expansion and contraction caused by the cold and hot degree of gas in the glass ball. This instrument is not very accurate and inconvenient to use because of the influence of air pressure fluctuation. The first practical thermometer in the world is an alcohol thermometer with the same reading, which was made by Warren Hite, an instrument manufacturer who moved from Germany to the Netherlands, from 1709. Later, the mercury thermometer was also invented and gradually evolved into the current thermometer. Modern technology gave birth to the electronic thermometer. The electronic thermometer uses the electrical signal output by the temperature sensor to directly output a digital signal, or converts the current signal (analog signal) into a digital signal that can be recognized by the internal integrated circuit, and then displays the temperature in digital form through the display (such as liquid crystal, digital tube, LED matrix, etc.). ), you can record and read the highest value of the measured temperature.

Hydrohydrometer: Hydrohydrometer is an instrument for measuring the density of liquid, which is made according to Archimedes principle, when an object floats on the liquid surface, it is in a state of equilibrium. It is a closed glass tube, one end of which is even in thickness, and the inner wall is pasted with scale paper, with uneven scale, thin on the top and dense on the bottom, and the other end is slightly expanded into a bubble shape, and the bubble is filled with small lead particles or mercury, so that the glass tube can be vertically immersed in the measured liquid to a sufficient depth, and can float stably in the liquid, that is, it can automatically return to the vertical static position when shaking. When a hydrometer floats in a liquid, its own gravity is equal to the gravity of the liquid it displaces. So when immersed in different liquids with different depths, the pressure is different. Use this relationship to calibrate the hydrometer.

Dynamometer: Now the commonly used dynamometer is spring dynamometer, so I will talk about the principle of spring dynamometer. First of all, any measurement is a process of comparing a physical quantity with a standard (that is, a unit), and the measurement of force is a process of comparing the effect of force with that of known force. If the action of a force is the same as that of 1 Newton, then the force is 1 Newton. Secondly, the elongation of the spring is proportional to the force. After determining the action of 1 Newton force, it is easy to determine the action of larger force and smaller force. In addition, the spring has good stability and can be reused. Therefore, the spring dynamometer can be used to measure the force.

Sundial: The sundial is a time measuring tool made by the ancients according to the principle that the position of the sun in a day (the direction of light projection) is also different. See/link? URL = SNF CJ 0 rnzo 4 vdvngydkgbhu 3 l5 bacv 9 mkd 0 qdsa 6 ldfpo 1 GK 5 teklytly Yu 98 T2 ympknt 0 uwu 4 IRQ btr 7 dn 9 NW wr 7 je 5 ogr qwvk 6 hgdas