Question

A U tube is made of two capillary tubes of diameter 0.5 mm and 1.0 mm respectively. It contains H₂O. (Surface tension 75 dynes/cm). Find the difference in two levels.

• A. (a) 2.4 cm
• A. (b) 2.6 cm
• A. (c) 2.8 cm
• A. (d) 3.0 cm

Answer 1

(d)

h = $\frac{2T}{\rho rg}$

∆h = $\frac{2T}{\rho g}\left\lbrack \frac{1}{r_{1}} - \frac{1}{r_{2}} \right\rbrack$

= $\frac{2 \times 75}{1 \times 980}\left\lbrack \frac{1}{.025} - \frac{1}{.05} \right\rbrack = 3cm$