Practice question
Question
A soap bubble of radius 12mm has a surface tension of 0.024N/m. What is the excess pressure inside?
Explanation
Excess pressure in a bubble: ΔP = 4Sr. S = 0.024N/m, r = 12×10−3m. ΔP = 4×0.02412×10−3 = 8Pa. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 8 Pa. This satisfies dimensional consistency and physical conditions given, so option B is scientifically correct.