Question

On dipping a capillary of length 20 cm. In a liquid, the liquid rises in it upto a height of 8 cm. If the who arrangement is placed in a lift falling freely, then the height of liquid column in capillary will be:

• A. 6 cm
• B. 8 cm
• C. 16 cm
• D. 20 cm

Answer 1

The correct option is D 20 cm

length of Capillary $l=20cm$

we know,

rise of water in capillary aftert dipping

in a liquid of density $f$ and angle of contact ${}^{\prime }{\theta }^{\prime }$ is

$h=\frac{2T\cos \theta }{r\rho g},\begin{array}{c}\text{where}\\ r=\text{radius}\\ T=\text{surface tension.}\end{array}$

But, In case of freefall,

the accelecration $g$ is $,g=0$

$\therefore \because h\propto \frac{1}{g}$

and $g=0$

$\therefore h$ tends to infinity and since $1+s$ not

possible, water in capillary will rise upto

the maximum height of the capillary that

is $20cm$

Correct option is $\left(D\right)$