Q. A barometer tube reds $76\ cm$ of mercury. If the tube is gradually inclined at an angle of $60{^\circ}$ with vertical, keeping the open end immersed in the mercury reservoir, the length of the mercury column will be
A) $152\ cm$
B) $76\ cm$
C) $38\ cm$
D) $38\sqrt{3}cm$
Explanation
(a) $\cos{60{^\circ} = \frac{h}{l}}$
$\Rightarrow l = \frac{h}{\cos{60{^\circ}}} = \frac{76}{1/2}$
$\therefore l = 152\ cm$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.