DiBeos

One of the easiest ways to understand flux is to think about how much of a vector field passes through a surface. If the field goes straight through, the flux is large. If it is almost parallel to the surface, the flux is small. If it points through the surface in the opposite direction, the flux is negative.

For a flat surface, this idea is captured by the dot product: only the component of the field perpendicular to the surface contributes. For a curved surface, calculus lets us add up all those tiny contributions:

– DiBeos

P.S. Flux shows up everywhere in physics., like in electric fields, magnetic fields, fluid flow, heat transfer, etc. All of them use the same idea of measuring how much “passes through” a surface.