# Question No.2

Calculate the capillary rise in mm in a glass tube of 6 mm diameter when immersed in (a) water, and (b) mercury, both liquids being at 20oC. Assume σ to be 73 × 10−3 N/m  for water and 0.5 N/m for mercury. The contact angle for water and mercury are zero and 130o respectively.

### Given :

• Glass tube of diameter D = 6 mm
• $θw=0o$
• $θHg=130o$

### Solution :

When the glass tube is immersed in water :

$Hw=4σwcosθwγwD$ $→$

$Hw=4∗73∗10−3∗cos0o9810∗0.006∗1000=4.96mm$

When the glass tube is immersed in mercury :

$HHg=4σHgcosθHgγHgD$ $→$ $HHg=4∗0.5∗cos130o9810∗13.6∗0.006∗1000=−1.61mm$