Question

If the difference between pressure inside and outside of a soap bubble is 6mm of water and its radius is 8mm. What is the surface tension in dynes per cm.

Answer 1

Pressure difference between inside and out side is related with the surface tension (T) and radius (r) of the bubble as follows.

Here pressure difference Pi-Po = pressure of 6 mm water column

=6*10^-1*1*980 dyne/cm²

=588 dyne/cm²

So T= (Pi-Po)*r/4

=>T = (588*8*10^-1)/4 dyne/cm

=>T = 117.6 dyne/cm

Answer 2

Here is another answer