The diagram below shows a simple mercury barometer. The mercury level is at a height h when the atmospheric pressure is 105 Pa.
What is the pressure at P?
Open in App
Solution
In a barometer, atmospheric pressure is directly proportional to the height of the mercury level.
Now, height h corresponds to the pressure of 1,00,000 Pa.
So height 0.4 h will correspond to the pressure of 0.4 × 1,00,000 = 40,000 Pa.
Hence, pressure at P is 40,000 Pa.