 # Impedance of Free Space  View Notes

In physics, impedance of free space, also recognized as the characteristic impedance of free space, is a physical constant signified by Z0. This narrates the magnitude of the magnetic field and the electric field of electromagnetic radiation roaming through free space.

The impedance of free space (means the wave impedance of a simple wave in free space) is equal to the multiplication of the speed of light in vacuum c0 and the vacuum permeability μ0.

Before 2019, the magnitudes of both these constants were considered to be precise (they were arranged in the descriptions of the ampere and the meter respectively), and the rate of the impedance of free space was taken to be exact similarly.

However, with the redefinition of SI base units that approached into force on 20 May 2019, the impedance of free space is a matter to experimental measurement because only the speed of light in vacuum recollects a correctly distinct value.

### Value of Intrinsic Impedance of Free Space

It is explained as the square root of the proportion of permeability of free space to the permittivity of free space.

The particular value of the impedance of free space is universally acknowledged, and the elaborated value is-

The Impedance of free space Z0 = 376.73Ω.

### Intrinsic Impedance of Free Space Formula

Formula

The impedance of free space can be accurately inscribed as:

$Z_0=\frac{E}{H}=\sqrt{\frac{μ_0}{c_0}}=μ_0c_0=\frac{1}{ε_0c_0}$

Where,

μ0 is the magnetic constant

ε0 is the electric constant

C0 is called the speed of light in free space.

E is the electric field strength.

H is the magnetic field strength.

Z0 sometimes also denoted the admission of free space.

Let’s hope that you have agreed with the Impedance of free space or the characteristic Impedance of free space alongside units, values, and the formulations.

### Characteristics Impedance of Free Space

These are some answers start to appear as we consider these facts such as:

1. Characteristic impedance is a characteristic of any medium that can embrace the transmission of an electromagnetic wave irrespective of whether or not it is associated with a power source at one terminal and a load at the other end.

Characteristic impedance adjusts signal or the current passing through a conductor. But if there is no non-stationary energy at a certain point in time, that does not change the fact that the medium has a precise characteristic impedance.

A reel of coax in the ware-house has similar characteristic impedance as when it is wired into an active, working network.

2. Characteristic impedance, nothing like conventional impedance, is free of length or distance over which signals propagate. Consequently, the characteristic impedance of the universe is the equivalent of the characteristic impedance of a circuit navigating about 50 feet of free space.

3. The characteristic impedance of a vacuum is considered equivalent to that of dry air which has almost no effect on conductance.

4. The characteristic impedance of free space is equivalent to the sq root of the proportion of penetrability of free space (henrys per meter) to the penetrability of free space (farads per meter). It figures out about 377 Ω, and that is the characteristic impedance of the universe.

### Impedance of Free Space Derivation

The impedance of free space also recognized as the characteristic impedance of free space is a physical constant represented by Z0 which co-relates the magnitude of the magnetic field and the electric field of electromagnetic radiation traveling through free space.

The wave impedance in free space of plane waves is illustrated by:

$Z_0=\frac{E}{H}=\sqrt{\frac{μ_0}{ε_0}}$

Here ε0 is the permittivity constant in the free space and μ0 is the permeability constant in free space and:

$c_0=\frac{1}{\sqrt{μ_0ε_0}}$ = 299,792,458 m/s

By the SI definition of the meter

As the values are exact, the value of Z0 in ohms is:

Z0=μ0c0 =4π×$10^{-7}\frac{H}{m}$ × 299,792,458$\frac{m}{s}$=376.73Ω

### Do You know?

Is there any characteristic impedance in the universe? If yes, then what is the value?

The universe is collected of huge quantities of blank space between relatively small stars broadly spaced apart. It is believed that when our Milky Way and the Andromeda Galaxy encounter 4 billion years from now, not even one star from galaxies will truly strike.

Scientists explain if stars were the size of balls like ping pong, they would be spread out on the order of two miles apart. However, there will undoubtedly be no collisions; both galaxies will be deeply exaggerated by the connections of their enormous gravitational fields.

Employing an electrical channel with characteristic impedance, the universe was possibly built with enhanced quality control than our best coaxial cable.

Q1. Explain the Transmission of an Electromagnetic wave in Free Space?

Ans- Characteristic impedance is a characteristic of any medium that can hold the transmission of an electromagnetic wave anyway, whether or not it is associated with a power source at one terminal and a load at the other end.

Characteristic impedance adjusts the current or signals traveling through a conductor.

Q2. Describe the independent factors of the Characteristic Impedance of Free Space?

Ans- It is independent of length or distance over which signals propagate. The characteristic impedance of the universe is equal to the characteristic impedance of a circuit traversing (let us say) 50 feet of free space.

Q3. What is the impedance of Free Space, and What is its use?

Ans- The impedance of free space denoted as Z0 is a constant which is a ratio of the magnitudes of the electric/magnetic fields and electromagnetic radiation traveling through free space. That is, Z0 = |E|/|H|

Where |E| = electric field strength and |H| = magnetic field strength.

Currently, its recognized value is;

Z0 = 376.730313668(57) Ω.

Q4. Let’s take an assumption and calculate the value of the impedance of Free Space, where Magnitudes of the Electric Field = 250.54 v/m and Magnetic Field H= 64.67 T (Tesla)?

Ans- Here are some parameters are given in the question such as

Electric field E = 250.54 v/m

Magnetic field H= 64.67 T

Then the value of the impedance of free space can be calculated as below

Z0 = E/H =250.54/64.67 = 3.87Ω

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