If E field points up, which way does B field point?

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SUMMARY

In a classical electromagnetic wave, when the electric field (E) points upward and the wave propagates to the right, the magnetic field (B) points towards the observer. This conclusion is derived from the right-hand rule, where the Poynting vector (S) indicates the direction of wave propagation. The confusion arises from inconsistent representations in textbooks, which can lead to misinterpretation. The correct relationship is established through the vector cross product of E and B, confirming that B points towards the observer in this scenario.

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  • Understanding of electromagnetic wave propagation
  • Familiarity with the right-hand rule in vector analysis
  • Knowledge of the Poynting vector and its significance
  • Basic concepts of electric and magnetic fields
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  • Study the right-hand rule in electromagnetic theory
  • Learn about the Poynting vector and its applications in wave mechanics
  • Explore common misconceptions in electromagnetic field representations
  • Review classical textbooks on electromagnetism for accurate depictions of E and B fields
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Students of physics, educators teaching electromagnetism, and professionals in electrical engineering seeking clarity on electromagnetic wave behavior.

Usaf Moji
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Ok, dumb question, I know. But it's been bugging me, and I can't find a straight answer anywhere, so here it goes:

In a classical electromagnetic wave, where the electric field points upward, will the magentic field point AT me or AWAY from me?

I've seen textbooks depict them both ways - can it really be both ways, or is it just sloppyness on the part of the drafters?

All responses appreciated.
 
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What is the vector definition of the Poynting vector?
 
berkeman said:
What is the vector definition of the Poynting vector?

Ah, I forgot to mention that I'm imagining the electromagnetic wave propagating to our right-hand side. So, I go E cross B with S pointing in the direction of propagation...to answer my own question, the magnetic field must point AT me...and, yes, the opposite depiction in some textbooks must be a drafting error.

Thank you, Berkeman
 
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