Question

If we use water, instead of mercury, as a barometric liquid,

• A. the glass tube needs to be much longer
• B. the glass tube needs to be of same length
• C. the glass tube needs to be much shorter
• D. the glass tube needs to be narrower

Answer 1

The correct option is A the glass tube needs to be much longer

Mercury is the heaviest liquid. Therefore, it rises only to a height of $76cm$ to balance the atmospheric pressure. Water, being $13.6$ times lighter than mercury, will rise to a $13.6$ times larger height. So, the glass tube needs to be much longer.