Question

What should be the diameter of a soap bubble such that the excess pressure inside it is 51.2 Pa? [Surface tension of soap solution = 3.2 × 10⁻² N/m]

Answer 1

p − p₀ = 51.2 Pa, T = 3.2 × 10⁻² N/m

For a soap bubble, p = p₀ = `(4T)/R`

∴ R = `(4T)/(p - p_0)`

∴ The diameter of the soap bubble should be

= `2R = (8T)/(p - p_0)`

= `(8 xx 3.2 xx 10^-2)/51.2`

= `3.2/6.4 xx 10^-2`

= 5 × 10⁻³ m

= 5 mm