# Interaction Between Magnetic and Electric Field Lines

• Drakkith
In summary, when a magnetic field and an electric field are present, their interaction results in the formation of field lines. These lines show the direction and strength of the fields and can either attract or repel each other depending on their orientation. The intersection of these field lines can create unique patterns and can be used to understand the behavior and properties of electromagnetic fields. This interaction is fundamental in many natural phenomena and is also utilized in various technologies such as electric motors and generators.
Drakkith
Mentor
Hey all. I was wondering what the interaction between Electric and Magnetic field lines are. For example, when you hold up a magnet against a charged electrode. I tried searching in google, but everything just turned up one or the other or how a moving charge makes a magnetic field and etc.

It's all about relative motion. If the electric field (or charged particles) and the magnetic field are not moving relative to one another then their interaction is governed by the rules of Electrostatics. If there is relative motion then their interaction is governed by what used to be known as Electrodynamics, now commonly referred to as Electro-Magnetism in acknowledgment of the intimate connection between electricity and magnetism.

Einstein's original paper "Zur Elektrodynamik bewegter Körper" ("On the Electrodynamics of Moving Bodies") is what became known as the Special Theory of Relativity.

I don't really know what you mean by that. Are you saying that a static magnetic and electric field act just like two electric fields?

In a static situation (like holding a magnet near a charge) there is no interaction.

Electro-statics and Magneto-statics are completely independent from each other.
The electric field is completely determined by the static distribution of charge (Gauss's law).
And the magnetic field is completely determined by static current (Ampère's circuital law).

However, when the electric field changes or the magnetic field changes, they start to interact (Maxwell's extension to Ampère's circuital law and Faraday's law).

So if you wave your magnet near an electric charge, things become more complicated.
(Like waving a magic wand! )

What exactly do you mean by no interaction? The magnet wouldn't repel or attract the electrode?
Do you happen to know where a diagram of the field lines for both the electric field and magnetic field in the same picture is?

Drakkith said:
What exactly do you mean by no interaction? The magnet wouldn't repel or attract the electrode?

Yes, that is what I mean.

Drakkith said:
Do you happen to know where a diagram of the field lines for both the electric field and magnetic field in the same picture is?

The only diagrams I'm familiar with that show both fields, is where it is explained how light works.
Like this one:
http://spot.pcc.edu/~aodman/physics%20122/light-electro-pictures/electromag-wavelength.jpg

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I like Serena said:
Yes, that is what I mean.

Thanks!

I think what the OP is getting at is what if you have a solenoid, and place an infinite charged plane parallel to the solenoidal axis? Then isn't there a nonzero Poynting Flux (ExB)? But how can this be if the fields are static?

RedX said:
I think what the OP is getting at is what if you have a solenoid, and place an infinite charged plane parallel to the solenoidal axis? Then isn't there a nonzero Poynting Flux (ExB)? But how can this be if the fields are static?

Yeah, that's a good example. I don't know about the infinite plane though. How would a realistic electrode, like about the size of the solenoid, react?

Drakkith said:
Yeah, that's a good example. I don't know about the infinite plane though. How would a realistic electrode, like about the size of the solenoid, react?

I don't know the answer to this. Here's a http://www.sheromov.com/files/Poynt.pdf" that has the paragraph:

"At carefully examination of Maxwell’s equations and sequence of their conclusion (for example, [1]) it is visible, that these equations describe only variables electric and magnetic fields which cause each other. Nevertheless, many authors (even in textbooks on the physics for high schools) try to apply them and, in particular, Poynting’s vector to stationary fields. It leads to absurdity. For example, flowing of energy of a field from an environment to a conductor with a direct current, or existence of some stream of energy about located close each other a constant magnet and the charged condenser."

and the last part about a stream of energy located close to a constant magnet and charged condenser is what I thought you were asking.

I do know that it is true that the energy of a field flows into the conductor of direct current. Surrounding a wire are B-field circles, and inside the wire are E-fields, so ExB suggests that energy is flowing into the wire. That makes sense because the wire is guiding electromagnetic waves into the resistor, thereby heating it up. But having a constant magnet and charged condenser confuses me. If you orient them so that E and B are perpendicular, then there should be an energy flow? Are they interacting somehow to give an energy flow?

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joobeng
Hrmmm...interesting...

## 1. How do magnetic and electric field lines interact?

The interaction between magnetic and electric field lines is known as electromagnetic interaction. This occurs when electric charges in motion produce a magnetic field, which in turn can influence the motion of other electric charges. This interaction is fundamental to many natural phenomena, such as the production of light and the functioning of electric motors.

## 2. What is the direction of the interaction between magnetic and electric field lines?

The direction of the interaction between magnetic and electric field lines is perpendicular to both the magnetic and electric fields. This means that the magnetic field lines will exert a force on the electric charges in the electric field, causing them to move in a direction perpendicular to both fields.

## 3. How does the strength of the magnetic field affect the interaction with electric field lines?

The strength of the magnetic field has a direct impact on the strength of the interaction with electric field lines. A stronger magnetic field will exert a stronger force on electric charges in the electric field, leading to a more significant interaction between the two fields.

## 4. What is the role of charged particles in the interaction between magnetic and electric field lines?

Charged particles play a crucial role in the interaction between magnetic and electric field lines. This is because these particles produce both electric and magnetic fields, and their motion can be influenced by the fields produced by other charged particles. Additionally, the interaction between the fields can cause charged particles to accelerate, producing a variety of effects.

## 5. What are some practical applications of the interaction between magnetic and electric field lines?

The interaction between magnetic and electric field lines has numerous practical applications. Some examples include generators, which use the interaction to produce electricity, and electric motors, which use the interaction to convert electrical energy into mechanical energy. Additionally, many modern technologies, such as MRI machines and particle accelerators, rely on the principles of electromagnetic interaction.

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