The problem statement, all variables and given/known data The mercury level in the barometer at sea level is recorded to be 76cm. So, I was wondering if you use a thinner tube. Will the mercury level change? At sea level, the pressure is 1 atm and thus according to the equation, p = hpg, whereby pressure is equal to the height of the mercury multiply by its density multiply by gravitational field strength, a thinner tube does not affect the mercury level and thus, it will not change. But, I came across something called capillary action, whereby the height of the mercury level is affected by the radius of the tube. So, will the mercury level change?