Question

The rate of flow of a liquid through a capillary tube is:

• A. directly proportional to the length of the tube.
• B. inversely proportional to the difference of pressure between the ends of the tube.
• C. directly proportional to the 4th power of the radius of the tube.
• D. independent of the nature of the liquid.

Answer 1

Answer: (C)

directly proportional to the 4th power of the radius of the tube.

According to poiseuille's equation, the rate of flow of a liquid in capillary tube is given by
$Q=\frac{\pi r^4\Delta P}{8\mu L}$
where
$Q=$flow rate
$r=$radius of the capillary tube
$\Delta P=$pressure difference
$L=$length of pipe/tube
$\mu =$coefficient of viscosity

Hence rate of flow of liquid through a capillary tube is directly proportional to the 4th power of the radius of the tube.
so the correct option is 'C'