Question

The moisture present in mercury ______ the barometric height of simple barometer

• A. increases
• B. decreases
• C. doesn't change
• D. can't say

Answer 1

The correct option is A increases

The instrument that measures air pressure is a barometer. There are two types of barometers, mercury and aneroid. In 1643, Toricelli invented the mercury barometer when he inserted a glass tube in a dish of mercury and observed the day-to-day variations in the height of the mercury column. When the atmospheric pressure was high, the greatest pressure was exerted on the mercury in the dish, causing the mercury in the glass tube to rise. When the pressure was low, the mercury in the glass tube fell. The contemporary aneroid barometer employs a vacuum chamber sensitive to external pressure changes. Contraction and expansion of the vacuum chamber, linked mechanically to an indicator needle, move the needle clockwise when the pressure rises and counter clockwise when the pressure falls.