Question

When a capillary tube is connected to a pressure head, V c.c. of water flows per second. If a tube of same length but half the radius is connected to the same pressure head, the quantity of water flowing through the tube per second will be ( in c.c):

• A. $\frac{V}{4}$
• B. V
• C. $\frac{V}{16}$
• D. $\frac{V}{8}$

Answer 1

The correct option is C $\frac{V}{16}$

$V=\frac{\pi P{r}^4}{8\eta l}$

$V_1=\frac{\pi P(r/2{)}^4}{8\eta l}$

Now, radius is $=r/2$

$V_1=V/16$