A tube of conical bore is dipped into water with apex upwards. The length of the tube is 20cm and radii at the upper and lower ends are 0.1 and 0.3 cm. Find the height to which the liquid rises in the tube ( Surface tension of water = 80 dyne `//` cm ).

Explanation

To solve the problem step by step, we will follow the principles of capillarity and the geometry of the conical tube.

### Step 1: Understand the Problem
We have a conical tube dipped in water with the apex upwards. The length of the tube is 20 cm, and the radii at the upper and lower ends are 0.1 cm and 0.3 cm, respectively. We need to find the height to which water rises in the tube, given the surface tension of water is 80 dyne/cm.

### Step 2: Use the Formula for Capillary Rise
The formula for the height of liquid rise in a capillary tube is given by:
\[
...