Question

What is the relation between electric field intensity and flux density?

Answer 1

The electric field intensity (**E**) and electric flux density (**D**) are related through the **permittivity** of the material in which the electric field exists. The relationship can be expressed as:

\[
D = \epsilon E
\]

Where:
- **D** is the electric flux density (measured in coulombs per square meter, C/m²).
- **E** is the electric field intensity (measured in volts per meter, V/m).
- **ε (epsilon)** is the permittivity of the material (measured in farads per meter, F/m). This value represents how much the material resists or allows the electric field to pass through it.

In simple terms:
- **Electric field intensity (E)** tells you how strong the electric field is at a point.
- **Electric flux density (D)** represents how much electric flux (charge) is passing through a unit area, and it depends on the electric field and the material's properties.

In vacuum, the permittivity is denoted as **ε₀**, which is approximately **8.85 × 10⁻¹² F/m**. In other materials, **ε** is typically greater than ε₀ due to the material's ability to store electric energy (its permittivity).

So, the electric flux density is essentially the product of the electric field and how the material responds to that field (its permittivity).