P pressure
Five volumes
NR constant
Test temperature
It contains an empty metal box with a certain volume of gas. According to the formula, when the temperature is constant, the greater the air pressure, the greater the volume. The expansion of the box uses the lever principle to transfer the force to the dial and cause the indicator to change.
The empty box barometer consists of a flat metal diaphragm empty box group, and the air pressure in the box is low. Based on the principle of balance between elastic stress and atmospheric pressure, the atmospheric pressure is measured by its deformation and displacement. Its advantages are easy to carry and install. However, because the elastic coefficient of metal diaphragm changes with temperature, temperature compensation measures must be taken; There is elastic lag in the deformation of the empty box, and the deformation curves of pressurization and decompression do not coincide in a certain air pressure range. The above two factors make the measurement accuracy of empty box barometer lower than that of mercury barometer. Empty-box barometer is made by using the principle of empty-box barometer, which can record automatically.
Empty box barometer is a kind of barometer. Its main part is a vacuum metal box with ripples on its surface. In order to prevent the metal box from being crushed by atmospheric pressure, the elastic steel sheet is pulled outward. With the increase of atmospheric pressure, the box cover is sunken; When the atmospheric pressure drops, the elastic steel sheet will pull the cover up a little. The change of the box cover is transmitted to the pointer through the transmission mechanism, which makes the pointer deflect. From the reading on the dial below the pointer, you can know the value of atmospheric pressure at that time. It is convenient to use and carry, but the measurement result is not accurate enough. If the dial of an aneroid barometer is marked with altitude instead of atmospheric pressure, it becomes an altimeter for aviation and mountaineering.
When the temperature is high on sunny days, gas molecules move higher than on cloudy days. Under the same volume, the more intense the movement of gas molecules, the higher the air pressure ~