Understanding Millimeter of Mercury

A Millimeter of Mercury(mmHg) is by definition the pressure exerted on a column of mercury 1 mm in height. 


I found this definition confusing because it doesn't say how the diameter of the container will affect the pressure. 




Pressure is defined as force exerted **per unit area.** Therefore, the diameter of the mercury column is taken into account when we calculate the area of the column. A mercury column with a large diameter will exert a greater force than a column of the same height, but with a smaller diameter - but the force divided by the area will be the same.


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