Physical meaning of parts of electromagnetic wave

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SUMMARY

The discussion centers on the physical interpretation of the term "k dot r" in the context of electromagnetic waves, specifically the equation E = E_0 exp(i(k dot r - wt)). It is established that "k dot r" represents the spatial phase of the wave, and that the position vector r can be any point in space, not limited to the wave itself. The conversation emphasizes that a 3-dimensional plane wave occupies all of space rather than being confined to a single line or path, as clarified by a referenced diagram in the forum.

PREREQUISITES
  • Understanding of electromagnetic wave equations, specifically E = E_0 exp(i(k dot r - wt))
  • Familiarity with vector dot products and their physical significance
  • Knowledge of wave propagation concepts in three-dimensional space
  • Basic grasp of plane wave characteristics and their representations
NEXT STEPS
  • Study the mathematical derivation of electromagnetic wave equations
  • Explore the physical implications of vector dot products in wave mechanics
  • Investigate the properties of plane waves and their applications in physics
  • Review visual representations of electromagnetic waves to enhance spatial understanding
USEFUL FOR

Students of physics, educators teaching wave mechanics, and researchers exploring the properties of electromagnetic waves will benefit from this discussion.

littlepapa87
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E = E_0exp i(k dot r - wt) or E = cos(k dot r - wt)

what does k dot r physically represent? Can r be any position in space or must it lie on the wave?

(I physically understand what a dot product is)
 
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That's a plane wave, it occupies all of space.

If you want a beam that is localized along a line, E_0 has to be a function of distance from the line.
 
littlepapa87 said:
Can r be any position in space

Yes.

or must it lie on the wave?

A 3-dimensional plane wave fills space. It doesn't lie "along" a line or other single path. See the diagram and associated instructions in the following post for a more realistic picture of a plane electromagnetic wave than you see in many textbooks.

https://www.physicsforums.com/showpost.php?p=533190&postcount=6
 

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