Poiseuille’s law is a scientific formula that describes the flow of fluids, such as liquids or gases, through a narrow tube or pipe.

It states that the rate of flow is directly proportional to the fourth power of the radius of the tube and the pressure difference between the two ends of the tube, but is inversely proportional to the viscosity of the fluid and the length of the tube.

In simpler terms, this means that if you have a narrow tube or pipe, increasing the pressure difference between the two ends of the tube, or increasing the radius of the tube, will increase the flow rate of the fluid.

On the other hand, increasing the viscosity of the fluid, or the length of the tube, will decrease the flow rate.