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

In summary, the conversation revolves around the direction of the magnetic field in a classical electromagnetic wave and whether it points towards or away from the observer. The questioner mentions seeing depictions of both directions in textbooks and wonders if it could be due to drafting errors. The conversation ends with the questioner finding the answer and thanking another person for their contribution.
  • #1
Usaf Moji
72
0
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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  • #2
What is the vector definition of the Poynting vector?
 
  • #3
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
 
Last edited:

1. What is the relationship between E field and B field?

The E and B fields are two components of the electromagnetic field, which is a fundamental force of nature. They are connected through Maxwell's equations, which describe how electric and magnetic fields interact with each other.

2. If the E field points up, does the B field also point up?

Not necessarily. The direction of the B field is determined by the right-hand rule. If you point your thumb in the direction of the E field, your fingers will curl in the direction of the B field. So depending on the orientation of your hand, the B field could point up, down, or even sideways.

3. Can the E field and B field be pointing in opposite directions?

Yes, they can. In some situations, such as in electromagnetic waves, the E field and B field are perpendicular to each other and have opposite directions. This is a result of the changing electric and magnetic fields propagating through space.

4. What happens if the E field and B field point in the same direction?

If the E field and B field point in the same direction, they will reinforce each other and create a stronger electromagnetic field. This is often seen in situations where there is a strong and steady current, such as in a wire carrying electricity.

5. Can the direction of the E field and B field change?

Yes, the direction of the E field and B field can change depending on the situation. In some cases, they may oscillate back and forth, while in others, they may remain constant. The direction of the fields can also be manipulated by external forces such as magnets or electric charges.

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