Flux

Definition

Electric flux measures the quantity of electric field passing through a given area. It is mathematically represented as $\Phi_E = E \cdot A \cdot \cos(\theta)$, where $E$ is the electric field, $A$ is the area through which the field lines pass, and $\theta$ is the angle between the field lines and the normal to the surface.

5 Must Know Facts For Your Next Test

1. Electric flux is a scalar quantity.
2. The SI unit for electric flux is volt-meters (V⋅m).
3. Gauss's Law relates electric flux through a closed surface to the charge enclosed by that surface: $\Phi_E = \frac{Q_{enc}}{\epsilon_0}$.
4. Electric flux can be positive, negative, or zero depending on the orientation of the electric field relative to the surface.
5. For a uniform electric field and a flat surface perpendicular to it, electric flux simplifies to $\Phi_E = E \cdot A$.

Review Questions

• What is the relationship between electric flux and Gauss's Law?
• How does changing the angle between an electric field and a surface affect the electric flux?
• What are the units of electric flux?

Related terms

Electric Field: A vector quantity representing the force per unit charge exerted on a positive test charge at any point in space.

Gauss's Law: $$\Phi_E = \frac{Q_{enc}}{\epsilon_0}$$; it states that the total electric flux through any closed surface is equal to the net charge enclosed divided by permittivity of free space.

$\epsilon_0$ (Permittivity of Free Space): $8.85 \times 10^{-12} \, F/m$; A constant representing how much resistance is encountered when forming an electric field in a vacuum.