Question

Water rises up to a height of $5cm$ in a capillary tube of radius $2mm$. What is the radius of the capillary tube if the water rises up to a height of $10cm$ in another capillary tube?

• A. $4mm$
  
• B. $1mm$
  
• C. $3mm$
  
• D. $2mm$
  

Answer 1

The correct option is B $1mm$

Since height of capillary rise is inversely proportional to radius of the capillary hence,

$h\alpha \frac{1}{r}$

$\frac{h_1}{h_2}=\frac{r_2}{r_1}\Rightarrow \frac{5cm}{10cm}=\frac{r_2}{2mm}$

$r_2=1mm$