Electric flux

Definition

Electric flux quantifies the number of electric field lines passing through a given surface. It is mathematically represented as the surface integral of the electric field over that surface.

5 Must Know Facts For Your Next Test

1. Electric flux is represented by the symbol $\Phi_E$ and is calculated using $\Phi_E = \int \vec{E} \cdot d\vec{A}$.
2. The SI unit for electric flux is volt-meters (V·m) or equivalently, newton-meters squared per coulomb (N·m²/C).
3. Gauss's Law relates electric flux to the charge enclosed within a surface: $\Phi_E = \frac{q_{enc}}{\varepsilon_0}$.
4. For a closed surface, positive electric flux indicates field lines leaving the surface, while negative flux indicates field lines entering it.
5. Electric flux through a closed surface enclosing no charge is zero, according to Gauss's Law.

Review Questions

• How do you calculate electric flux through a given surface?
• What does Gauss's Law state about the relationship between electric flux and enclosed charge?
• What would be the electric flux through a closed surface with no enclosed charge?

Related terms

Gauss's Law:

A fundamental law stating that the total electric flux through a closed surface is equal to the charge enclosed divided by the permittivity of free space.

Surface Integral:

\( A mathematical operation used to calculate quantities distributed over a curved or flat surface. In physics, it often applies to fields like electromagnetism. \)

$\varepsilon_0$ (Permittivity of Free Space): \( A physical constant representing the capability of a vacuum to permit electric field lines. Its approximate value is $8.854 \times 10^{-12}$ F/m (farads per meter). \)