Laplace’s Law states that the pressure difference ($\Delta P$) across the walls of a spherical shell is directly proportional to the tension ($T$) in the wall and inversely proportional to the radius ($r$) of the sphere. Mathematically, it can be expressed as:

​

Where:

• $\Delta P$ is the pressure difference across the wall,
• $T$ is the surface tension of the fluid, 
• $r$ is the radius of the spherical shell.