What is wave impedance of free space

The wave impedance of free space, also known as the characteristic impedance of free space ($Z_0$), is a fundamental constant in electromagnetics. It represents the ratio of the electric field ($E$) to the magnetic field ($H$) in an electromagnetic wave propagating through free space.

The value of the wave impedance of free space is given by the formula:

Where:

• $mu_0$ is the permeability of free space (vacuum permeability), which is approximately $4pi times 10^{-7} , text{H/m}$ (henries per meter).

• $epsilon_0$ is the permittivity of free space (vacuum permittivity), which is approximately $8.854 times 10^{-12} , text{F/m}$ (farads per meter).

By calculating this, we get:

So, the wave impedance of free space is approximately 377 ohms. This is the intrinsic impedance of a vacuum and is a key property when studying the behavior of electromagnetic waves in free space.