The reading of a faulty barometer is 700 millimetres of Hg when actual pressure is 750 mm of Hg. The length of the air column trapped in this case is 10 centimetres. Find the actual value of atmospheric pressure when reading of this barometer is 750 millimetres of Hg assume that the length of the Barometer tube above Hg surface in the container remains same

The faulty barometer reads 700mm of Hg whereas actual pressure is Pact=750mm of Hg and air pressure pa=100mm.So      Pact-pa=Pfaulty         pa=Pact-Pfaulty=750-700=50mm of Hg.The volume of air Va =100×A, where A is the area of the column.The air pressure of when actual pressure is 750mm of Hg is given by,   Va'=100×A +750-750A=100×A.Therefore according to the equation of pressure and volume,      Pa Va=Pa' Va'or  Pa'=Pa VaVa'=50×100A100A=50mm of Hg.Therefore actual pressure Pactual=750+50=800mm of Hg.The faulty barometer reads 700mm of Hg whereas actual pressure is Pact=750mm of Hg and air pressure pa=100mm.So      Pact-pa=Pfaulty         pa=Pact-Pfaulty=750-700=50mm of Hg.The volume of air Va =100×A, where A is the area of the column.The air pressure of when actual pressure is 750mm of Hg is given by,   Va'=100×A +750-750A=100×A.Therefore according to the equation of pressure and volume,      Pa Va=Pa' Va'or  Pa'=Pa VaVa'=50×100A100A=50mm of Hg.Therefore actual pressure Pactual=750+50=800mm of Hg.

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