A barometer tube reads $76\;cm$ of mercury. If the tube in gradually inclined at an angle of $60^{\circ}$ with vertical , keeping the open end immersed , in mercury reservoir, the length of the mercury column will be

$\begin {array} {1 1} (a)\;152\;cm \\ (b)\;90\;cm \\ (c)\;zero \\ (d)\;38\;cm \end {array}$

If l is the length of the mercury column when it is tilted we have
$l \cos 60^{\circ}=h=76\;cm$
$\large\frac{l}{2}$$=76^{\circ}$
$l=152 \;cm$
Hence a is the correct answer.

edited Feb 18, 2014 by meena.p