# How to insert an equation with integral

**Gauss's law**, also known as

**Gauss's flux theorem**.

How to add an equation in your document, see Working with Microsoft Equation.

To add integral form of the **Gauss's law**, do the following:

** 1. ** In the **Equation Editor** select **Contour integral with subscript limit** in the **Integral templates** group on the **Equation** toolbar:

** 2. ** Enter * S* in the lower box of your integral.

** 3. ** In the base box of the integral enter * E* and then choose

**Bullet**in the

**Operator symbols**group on the

**Equation**toolbar:

** 4. ** Enter * dA=*.

** 5. ** In the **Equation Editor** enter * f(x)=* and then select

**Full-size vertical fraction**in the

**Fraction and radical templates**group on the

**Equation**toolbar:

** 6. ** Enter * Q* in the top of this template and in the bottom:

- Choose in the
**Greek characters (lowercase)**group on the**Equation**toolbar: - Select
**Subscript**in the**Subscript and superscript templates**group on the**Equation**toolbar: - Enter
in the lower right box of script.**0**