Question

A barometer tube reads 76 cm of mercury. If the tube is gradually inclined keeping the open end immersed in the mercury reservoir, will the length of mercury column be 76 cm, more than 76 cm or less than 76 cm?  

Answer 1

The vertical height of the mercury column in the barometer tube remains 76 cm even if it is tilted. It is because the pressure at the reservoir level depends on the vertical height of the mercury (ρgh). The length of mercury in the tube will vary accordingly.