Question

Atmospheric pressure is measured by
(a). Barometer
(b). Manometer
(c). Screw gauge
(d). None of the above

Answer 1

Hint: Atmospheric is the pressure exerted by the earth’s atmosphere on a body. Gravity is responsible for the pressure exerted by the atmosphere. The word ‘Baro’ is a Greek word which means weight or pressure and meter can be defined as a scale of measurement.

Complete answer:
We know that the air around us has weight, and due to this reason, it presses against everything it touches that pressure is called atmospheric pressure or air pressure. Atmospheric pressure is measured using a barometer.
A Barometer is constructed in such a way that it has a long glass tube which is closed at one end and open at the other. This tube is filled with mercury and the tube is turned upside into a container containing mercury. The working principle of the barometer is by balancing the mercury in the glass tube against the outside atmospheric pressure. As atmospheric or air pressure increases, the mercury in the tube is pushed upwards. When the air pressure decreases, the mercury goes down in the tube, in such a way it acts like a scale which can be used to make a precise measurement of the air pressure.

Note: SI unit of atmospheric pressure is the same as that of pressure which is the Pascal (Pa). A manometer is an instrument used to measure gas pressure. One type of manometer is the open-manometer which measures the gas pressure relative to the atmospheric pressure. A screw gauge is a measurement device used to measure the dimension of objects accurately in the millimetre scale.