To understand the meaning of Electric Flux compare it with the watery flux. Mathematically these two conceptions are quite similar. By definition, Flux is the amount of something that passes through a surface. As for Electric flux, it is a measure of the electric field passed through a surface. The model illustrates what causes this electric flux and how its value depends on the value of the charge. The yellow line determines the area through which the electric field passes. You can vary the value of the charge and see how it changes the Electric flux. Or choose two charges and see how their disposition and values affects the value of the Electric flux. Fill checkbox ?Electric field? to see the lines of the electric field. This will help you to understand the varying of the Electric flux. You can also change the shape and position of the area by clicking and dragging it with the hand cursor. If you change the area so that the charge is out of the area, what is the flux value?