# For an electromagnetic wave poynting vector is represented by?

Last Update: April 20, 2022

This is a question our experts keep getting from time to time. Now, we have got the complete detailed explanation and answer for everyone, who is interested!

**Asked by: Thomas McKenzie**

Score: 4.4/5 (27 votes)

The Poynting vector S is defined as to be equal to **the cross product (1/μ)E × B**, where μ is the permeability of the medium through which the radiation passes (see magnetic permeability), E is the amplitude of the electric field, and B is the amplitude of the magnetic field.

## What does Poynting vector represent?

In physics, the Poynting vector represents **the directional energy flux (the energy transfer per unit area per unit time) of an electromagnetic field**. The SI unit of the Poynting vector is the watt per square metre (W/m^{2}). It is named after its discoverer John Henry Poynting who first derived it in 1884.

## How are electromagnetic waves represented?

Mathematical Representation of Electromagnetic Wave

The direction of propagation of the electromagnetic wave is given by vector cross product of the electric field and magnetic field. It is given as: **→E×→B E → × B → .**

## What are E and H in Poynting vector?

(1) **E is the electric field intensity, H is the magnetic field intensity, and P is the Poynting vector**, which is found to be the power density in the electromagnetic field. The conservation of energy is then established by means of the Poynting theorem. 2 The Poynting theorem.

## What will be the direction of the Poynting vector?

The direction of Poynting vector is **perpendicular to the direction of propagation of wave**. Explanation: The Poynting vector is proportional to the cross product of Electric and magnetic field, E X B. Therefore, its direction is perpendicular to Electric and Magnetic waves, i.e., in the direction of propagation of wave.

## 8.02x - Module 12.01 - EM Plane Waves - Poynting Vector - E-fields - B fields - Wavelength

**29 related questions found**

### Is Poynting a vector intensity?

The Poynting vector represents the direction of propagation of an electromagnetic wave as well as the energy flux density, or intensity. ... The constant in front serves to provide the correct magnitude for the intensity: **S ⃗ = 1 μ 0 E ⃗ × B ⃗** .

### What is the dimension of Poynting vector?

In the discussion of ray optics, we will see that the direction of the Poynting vector is identical to the direction of the light ray as normal vector of the plane formed by the electric and magnetic field vectors. Due to its physical dimension of **watts per area**, the Poynting vector corresponds to the ray's density.

### What is H EMW?

and →H. are **mutually perpendicular** and also they are perpendicular to the direction of propagation vector →k. . The velocity of propagation of electromagnetic waves is equal to the speed of light in free space. This indicates that the light is an electromagnetic wave.

### Which electromagnetic wave has highest wavelength?

**Radio waves** have the longest wavelength, and gamma rays have the shortest wavelength.

### What are the 7 wavelengths?

The EM spectrum is generally divided into seven regions, in order of decreasing wavelength and increasing energy and frequency. The common designations are: **radio waves, microwaves, infrared (IR), visible light, ultraviolet (UV), X-rays and gamma rays**.

### What are the 4 main properties of electromagnetic waves?

Every form of electromagnetic radiation, including visible light, oscillates in a periodic fashion with peaks and valleys, and displaying a **characteristic amplitude, wavelength, and frequency** that defines the direction, energy, and intensity of the radiation.

### What are the sources of electromagnetic waves?

Examples of EM radiation include radio waves and microwaves, as well as infrared, ultraviolet, gamma, and x-rays. Some sources of EM radiation include **sources in the cosmos (e.g., the sun and stars), radioactive elements, and manufactured devices**. EM exhibits a dual wave and particle nature.

### What are the applications of Poynting Theorem?

Conclusions. [31] Application of Poynting's Theorem to **electromagnetic energy transfer between the magnetosphere and ionosphere**, based on observations of the perturbation Poynting vector S_{p} above the ionosphere, gives an accurate quantitative measure of this transfer in a spatially integrated sense.

### What is meant by Poynting Theorem?

: a statement in electromagnetic theory: **the transfer of energy by an electromagnetic wave is at right angles to both electric and magnetic components of the wave vibration and its rate is proportional to the vector product of their amplitudes**.

### What is radiation intensity and explain in terms of Poynting vector?

In most of them **the flux of energy associated to** electromagnetic radiation is described in terms of the time average of the Poynting vector. This average is related to the square of the amplitude of the electric field and it is called “intensity” or “power density”.

### Is electric field a wave?

The electric field describes **an electromagnetic wave completely in free space**. The magnetic field is related to the electric field by a simple relationship. Start from Faraday's law.

### How are E and H fields related?

Keeping it simple, the rate of energy transfer per unit area (power density) is the product of the electric field strength **(E) times the magnetic field strength (H)**. where P_{d}= the power density, E = the electric field strength in volts per meter, H = the magnetic field strength in amperes per meter.

### What is Omega in electromagnetics?

The general solution to the electromagnetic wave equation is a linear superposition of waves of the form. for virtually any well-behaved function g of dimensionless argument φ, where **ω is the angular frequency (in radians per second)**, and k = (k_{x}, k_{y}, k_{z}) is the wave vector (in radians per meter).

### What is power flow and Poynting vector?

Here (W/mt2) is called the Poynting vector and it represents the **power density vector associated with the electromagnetic field**. The integration of the Poynting vector over any closed surface gives the net power flowing out of the surface.

### What is impedance of a wave?

The wave impedance of an electromagnetic wave is **the ratio of the transverse components of the electric and magnetic fields** (the transverse components being those at right angles to the direction of propagation).

### What is meant by displacement current?

: **a limited shifting of electric components that occurs within a dielectric when a voltage is applied to or removed from it** (as in charging or discharging a capacitor) and that corresponds to the current in the circuit supplying the voltage.

### What is J in Maxwell equations?

In the last equation, J is **the free current density**. For linear materials, the relationships between E, D, B, and H are.

### What is the value of intrinsic impedance in free space?

For a uniform plane wave traveling in a given medium, E/H is a constant and gives the intrinsic impedance. The value of intrinsic impedance corresponding to free space is 120π, which is approximately equal **to 377Ω**.

### What is the intensity of an electromagnetic wave?

Intensity generally refers to **a power per area (energy per area per time)**. For an electromagnetic wave, you can find its intensity by computing the magnitude of the Poynting vector, and in most circumstances taking its time average.