Question

A spherical drop of water has radius 1 mm if surface tension of context is 70 × 10^–3 N/m difference of pressures between inside and outside of the spherical drop is 

(A) 35 N/m² 

(B) 70 N/m² 

(C) 140 N/m² 

(D) zero

Answer 1

Correct option: (C) 140 N/m²

Explanation:

Difference of pressure = ΔP = (2T / R)

Given : T = 70 × 10^–3 N/m

R = 1 mm = 10^–3 m

Hence   ΔP = {(2 × 70 × 10^–3) / 10^–3} = 140 N/m²