Question

Water rises to a height of 2$cm$ in a capillary tube. If the radius of capillary tube is made ${\left(\frac{2}{3}\right)}^{rd}$ of its previous value, the height to which the water rises in the tube is

• A. $3cm$
• B. $6cm$
• C. $2cm$
• D. $3.5cm$

Answer 1

Answer: (A)

$3cm$

We know that

$h=\frac{2T}{\rho gr}$

So $h\propto \frac{1}{r}$

Now

$h_1{r}_1=h_2{r}_2$

$2\times r=h\times \frac{2}{3}r$

$H=3cm$

Answer: $\left(A\right)$