The excess pressure inside a spherical soap bubble of radius 1 cm is balanced by a column of oil (Specific gravity =0.8), 2 mm high , the surface tension of the bubble is

Question

The excess pressure inside a spherical soap bubble of radius 1 cm is balanced by a column of oil (Specific gravity =0.8), 2 mm high , the surface tension of the bubble is (A) 3.92 N / m (B) 0.0392 N / m (C) 0.392 N / m (D) 0.00392 N / m

Tardigrade Admin · Accepted Answer

The excess pressure of soap bubble p =(4 T/R) h ρ g =(4 T/R) ∴ T= (R h ρ g/4) =(1 × 10-2 × 2 × 10-3 × 0.8 × 103 × 9.8/4) = 3.92 × 10-2 N / m =0.0392 N / m

Q. The excess pressure inside a spherical soap bubble of radius $1 c m$ is balanced by a column of oil (Specific gravity $= 0.8), 2 mm$ high , the surface tension of the bubble is

3.92 N / m

0.0392 N / m

0.392 N / m

0.00392 N / m

The excess pressure of soap bubble
$p = \frac{4 T}{R}$
$h ρ g = \frac{4 T}{R}$
$∴ T = \frac{R h ρ g}{4}$
$= \frac{1 \times 1 0 ^{- 2} \times 2 \times 1 0 ^{- 3} \times 0.8 \times 1 0 ^{3} \times 9.8}{4}$
$= 3.92 \times 1 0^{- 2} N / m$
$= 0.0392 N / m$

Q. The excess pressure inside a spherical soap bubble of radius 1cm is balanced by a column of oil (Specific gravity =0.8),2mm high , the surface tension of the bubble is