Rather than using the dot product equation, let's use the electric flux equation  without the dot product.

我们不使用点积方程，而是使用不带点积的电通量方程。

We can substitute in the equation for the electric field  which surrounds a point charge and the equation for the surface area of a sphere into the electric  flux equation.

我们可以将点电荷周围的电场方程和球体表面积方程代入电通量方程。