# 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:

In the * Professional* present:

** 1. ** Create your own equation.

** 2. ** On the **Equation Tools Design** tab, in the **Structures** group, click the **Integral** button:

In the **Integral** list choose **Contour Integral**:

** 3. ** In the integral template:

- In the lower box enter
.**S** - In the upper box right-click and choose
**Hide Upper limit**in the popup menu: - In the base right box enter
.**E**

** 4. ** On the **Equation Tools Design** tab, in the **Symbols** group, in the list of symbols choose .

** 5. ** Then enter * dA=*.

** 6. ** On the **Equation Tools Design** tab, in the **Structures** group, click the **Fraction** button. In the **Fraction** list choose **Stacked Fraction**:

** 7. ** Enter * Q* in the top of your fraction.

** 8. ** In the bottom of your fraction, do the following:

- on the
**Equation Tools Design**tab, in the**Structures**group, click the**Script**button. - in the
**Script**list choose**Subscript**: - on the
**Equation Tools Design**tab, in the**Symbols**group, in the list of symbols choose , - in the lower box of the subscript enter
.**0**

In the * Linear* present:

** 1. ** Create your own equation.

** 2. ** Do one of the following:

- On the
**Equation Tools Design**tab, in the**Symbols**group, click the**More**button:In the top of list of symbols choose

**Operators**:

In the**Operators**list choose . - Simply enter
.**\oint**

** 3. ** Enter * _S*. Then you enter a space key, this linear formula transformed to the professional format.

** 4. ** In the base box of integral, enter * E*.

** 5. ** On the **Equation Tools Design** tab, in the **Symbols** group, choose (or simply enter * \bullet*).

** 6. ** Then enter * dA=Q/*, choose (or simply enter

*) and then*

**\varepsilon***:*

**_0**Then you enter a space key, your linear formula transformed to the professional format.