Question

The angle of contact between glass and water is 0o and it rises in a capillary upto 6 cm when its surface tension is 70 dynes/cm. Another liquid of surface tension 140 dynes/cm, angle of contact 60o and relative density 2 will rise in the same capillary by

• A. 12 cm
• B. 24 cm
• C. 3 cm
• D. 6 cm

Answer 1

The correct option is C 3 cm

$h=\frac{2Tcos\theta }{rdg}\therefore \frac{h_2}{h_1}=\frac{T_2}{T_1}\times \frac{cos{\theta }_2}{cos{\theta }_1}\times \frac{d_1}{d_2}\times \frac{r_1}{r_2}$
$\frac{h_2}{h_1}=\frac{140}{70}\times \frac{cos{60}^{\circ }}{0^{\circ }}\times \frac{1}{2}\times 1=\frac{1}{2}\Rightarrow h_2=\frac{h}{2}=3cm$.