Understanding Signals: In-Phase and Poynting Vector Explained

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Discussion Overview

The discussion revolves around the concepts of in-phase signals in electromagnetic waves and the Poynting vector, focusing on their definitions, representations, and relevance in the context of wireless communication. The scope includes theoretical explanations and conceptual clarifications.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant seeks clarification on what it means for two signals to be in phase, specifically mentioning that the electric (E) and magnetic (B) vectors in electromagnetic signals are always in phase.
  • Another participant explains that "in phase" means the crests and troughs of the signals coincide, referencing sine functions to illustrate this point.
  • A participant expresses difficulty in understanding the graphical representation of the Poynting vector, despite having received links for further information.
  • It is noted that the Poynting vector represents the flux of energy per unit area and is at right angles to both the electric and magnetic fields.
  • One participant questions the necessity of the term "Poynting vector," suggesting that the E and B components alone might suffice.
  • Responses clarify that the Poynting vector indicates the direction of energy movement, and naming such concepts aids in efficient communication among physicists.

Areas of Agreement / Disagreement

Participants express varying levels of understanding regarding the Poynting vector and its graphical representation. There is no consensus on the necessity of the term "Poynting vector," and the discussion includes both supportive and questioning viewpoints.

Contextual Notes

Some participants reference external sources for definitions and explanations, indicating potential limitations in the clarity of the concepts discussed. The discussion does not resolve the uncertainties surrounding the graphical representation of the Poynting vector.

dervast
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a)Hi i want to know what do we mean that 2 signals are in phase, For example in an electromagnetic signal the E and B vectors are always in the same phase right?

b)Also i am trying to find information about pounting vector.. It seems that the pounting vector denotes the flux of energy... Can u explain it more to me?
 
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Please consult HyperPhysics

When two quantities are "in phase," their crests are coincident, as are their troughs. Note on the linked page the equations:

emwv2.gif

emwv3.gif


Since the arguments of the sine function are the same, both fields have their maxima and minima at the same time, and are thus in phase.

Further down on the same page, you'll see the definition of the Poynting vector:

emwv5.gif


The Poynting vector represents the flux of energy per unit area.

- Warren
 
Last edited:
Thx a lot for your answers... I have aksed u about the Punting vector because we use it in a wireless lesoon.. I have written the links u gave me but for being honest i can still figure out (graphical representation can't be created) how the pounting vector is... Thx a lot Have a happy new year
 
Thx a lot for your answers... I have aksed u about the Punting vector because we use it in a wireless lesoon.. I have written the links u gave me but for being honest i can still figure out (graphical representation can't be created) how the pounting vector is... Thx a lot Have a happy new year
 
The electric and magnetic fields are at right angle to each other; the Poynting vector is at right angles to both.

If the electic field has oscillations in the x direction, and the magnetic field has oscillations in the y direction, then the Poynting vector is in the z direction.

The Poynting vector is in the direction in which the signal travels; the electric and magnetic fields are perpendicular to it.

- Warren
 
Thx and something more...why physicians have created the term pounting vector. E and B components of an Electromagnetic signal weren't enough for that?
 
1) They're called physicists, not physicians.
2) The vector is useful, because it points in the direction of the movement of energy.
3) Most things that are useful in math or physics are given names, so that communication between mathematicians or physicists can be made more efficient.

- Warren
 

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