A formal statement of the relation between charge and flux is known as Gauss? low. The low states: The total electric flux emerging from an arbitrary volume equals the net charge enclosed within the volume divided by ε0. In this model you can vary the charge and the radius of Gauss? sphere. Also, you can change the distribution of charges by choosing ?sphere? or ?shell? with radio buttons. Note that if the radius of Gauss? sphere is smaller than the radius of the shell and the charges are positive, the value of the flux is zero! Try different values of charge and different radii to understand how the flux depends on them.