Find the excess pressure inside (a) a drop of mercury of radius 2 mm (b) a soap bubble of radius 4 mm and (c) an air bubble of radius 4 mm formed inside a tank of water. Surface tension of mercury , soap solution and water are 0.46Nm−1,0.03Nm−1 and 0.076Nm−1 respectively.
r = 2 mm
=2×10−3m,
THg=0.465N/m
T8=0.03N/m,
Ta=0.076N/m
P = 2THgr
=0.465×22×10−3=465N/m2
P = 4T8r
= 4×0.034×10−3=30N/m2
P = 2Tar
= 2×0.0764×10−8=38N/m2