Question

The height of mercury barometer is $h$ when the atmospheric pressure is ${10}^{5}Pa$,The pressure at $x$ in the shown diagram is

• A. ${10}^{5}Pa$
• B. $0.8\times {10}^{5}Pa$
• C. $0.2\times {10}^{5}Pa$
• D. $120\times {10}^{5}Pa$

Answer 1

The correct option is B $0.8\times {10}^{5}Pa$

$h\rho g={10}^{5}Pa$ (given)
$\therefore$ $P_x=(h-\frac{h}{5})\rho g$
$=0.8h\rho g$
$=0.8\times {10}^{5}Pa$