Permeability vs Permittivity : Key differences

Introduction : Permeability vs Permittivity is a fundamental topic in electromagnetic theory that explains how materials interact with electric and magnetic fields. These two properties play a critical role in determining electromagnetic wave propagation, wave speed, impedance, reflection, and transmission in media. Understanding the key differences between permeability and permittivity is essential for applications in physics, electrical engineering, RF and microwave systems, antenna design, optics, and material science.

Permittivity: It is a material’s ability to permit electric field lines to pass through it, reflecting its capacity to store electric energy or its opposition to electric field formation.

• The relation between Electric displacement (D) and electric field intensity (E) are expressed as follows.

$𝜀 = D/E$

• Further, permittivity (ε) can be expressed by following formula.

$ε=ε0​ . εr​$

Where,

• ε0​ = permittivity of free space ( approximately equals to value of 8.854 x 10^-12 Farads per meter (F/m) )
• εr = Relative Permittivity (Dielectric Constant) ​

Permeability: It is a material’s ability to support the formation of a magnetic field, showing how easily magnetic flux lines pass through it.

• The relation between magnetic flux density (B) and magnetic field intensity (H) are expressed as follows.

$𝜇 = B/H$

• Further, permeability (μ​) can be expressed by following equation.

$μ=μ0 . ​μr​$

Where,

• μ0​ = Permeability of free space (approximately equals to value of 4. π . 10^-7 Henrys per meter (H/m))
• ​μr​ = relative permeability

Difference between permeability and permittivity

Summary:

The key difference between permeability and permittivity lies in the type of field they govern; permittivity controls electric field behavior, while permeability controls magnetic field behavior. Together, they determine how electromagnetic waves propagate through a medium, including wave velocity and intrinsic impedance.