Question

If the diameter of a soap bubble is 20 mm and if the surface tension of soap water is 0.04N.m${}^{-1}$, the excess pressure inside the bubble is in Nm${}^{-2}$ is :

• A. 0.16
• B. 1.6
• C. 0.016
• D. 16

Answer 1

The correct option is D 16

Excess pressure in bubble = $\frac{4T}{R}$
= $\frac{4\times \left(0.04\right)}{\frac{20}{2}\times {10}^{-3}}$
= 16 $N/m^2$
Hence, excess pressure is 16 $N/m^2$