A liquid column of height 0.04 cm balances excess pressure of a soap bubble of certain radius. If density of liquid is 8 103 kg m-3 and surface tension of soap solution is 0.28 N m-1, then diameter of the soap bubble is cm. (if g = 10 m s-2)
Answer
7
Solution
Soap bubble (two surfaces): P = 4Tr = gh
gh = 8 103 10 0.04 10-2 = 32 Pa
r = 4 0.2832 = 0.035 m = 3.5 cm
Diameter = 2r = 7 cm
Answer: 7