Question

A glass capillary tube of internal radius \(r = 0.25\,\text{mm}\) is immersed in water. The top end of the tube is projected by \(2\,\text{cm}\) above the surface of the water. At what angle does the liquid meet the tube? (Surface tension of water \(=0.7\,\text{N/m}\)).

• A. \(\theta = 90^\circ\)
• B. \(\theta = 70^\circ\)
• C. \(\theta = 45^\circ\)
• D. \(\theta = 35^\circ\)

Hint:

For capillarity: \[ h\propto \cos\theta \] Larger contact angle reduces rise.

Answer 1

The Correct Option is B