The instrument used for measuring atmospheric pressure is

The instrument used for measuring atmospheric pressure is a barometer. A barometer is an instrument that measures atmospheric pressure, which is the force exerted by the weight of the atmosphere on the Earth's surface. The most common type of barometer is the mercury barometer, which consists of a glass tube that is closed at one end and filled with mercury. The tube is then turned upside down and inserted into a container of mercury, which allows the mercury in the tube to settle at a certain height. The height of the mercury in the tube is directly proportional to the atmospheric pressure, with higher pressure pushing the mercury up the tube and lower pressure allowing the mercury to fall. The atmospheric pressure can be read by measuring the height of the mercury column in the tube against a scale. Other types of barometers include aneroid barometers, which use a flexible metal chamber to measure changes in atmospheric pressure, and digital barometers, which use electronic sensors to measure pressure changes. In summary, a barometer is the instrument used for measuring atmospheric pressure. The most common type is the mercury barometer, which measures the height of a column of mercury in a tube to determine the atmospheric pressure.