Question:
The lower end of a capillary tube of radius $1 \mathrm{~mm}$ is dipped vertically into mercury.
(a) Find the depression of mercury column in the capillary.
(b) If the length dipped inside is half the answer of part (a), find the angle made by the mercury surface at the end of the capillary with the vertical. Surface tension of mercury $=0.465 \mathrm{~N} / \mathrm{m}$ and the contact angle of mercury with glass $=135^{\circ}$.
Solution:
