Write the equation of excess pressure (pressure difference) for a bubble in air and a bubble in water.

(N/A) $1$. For a bubble in air (soap bubble): $A$ soap bubble has two surfaces in contact with air (inner and outer). The excess pressure $\Delta P$ is given by $\Delta P = \frac{4T}{R}$,where $T$ is the surface tension and $R$ is the radius of the bubble.
$2$. For a bubble in water (air bubble in liquid): An air bubble in water has only one surface in contact with the liquid. The excess pressure $\Delta P$ is given by $\Delta P = \frac{2T}{R}$,where $T$ is the surface tension of the liquid and $R$ is the radius of the bubble.