what can cause the electric and magnetic portions of an electromagnetic field to lose their relationship?

Question

Ok, so I was reading this article today about electromagnetic fields and it gave me a weird idea that leads me to a question. I learned in physics that electric fields and magnetic fields exist perpendicularly to one another as well as inversely in their magnitudes i.e. as one goes down the other goes up......what I inferred from this article was that this inverse magnitude thing is not necessarily always so, which is why complex numbers are useful in calculations involving this stuff....so my question is, what kind of circumstance would make it so there wasn't a direct 1:1 inverse relationship between the two i.e. one of them goes down, but the other doesn't go up as much as it should etc....

Answer 1

The relationship between magnetic and electric fields is determined by Maxwell's Equations. Time-changing electric fields produce magnetic fields and vice versa. The equations dictate that the direction of the fields are at right angles, but the magnitude is given by the time rate of change of the generating field. When you solve the equations for the condition that the time-changing electric field produces a time-changing magnetic field in such a way that the magnetic field is also time-changing, plus the nature of the time-changing magnetic field is such that it generates the same electric field that produced it, then you get a wave equation in which both fields form sinusoidal waves traveling at light speed. In this wave the magnitude of the electric and magnetic fields are 90º out of phase, so that the magnetic field reaches its peak when the electric field is zero and vice versa. This is what you are referring to as the "inverse relationship". This does not hold in the general case; for example, an electric field that is increased at a linear rate produces a constant (non-time-changing) magnetic field. So the electric field "goes up" but the magnetic field doesn't go at all. (Of course, this condition is not self-sustaining; some external input must keep the electric field increasing.)

Answer 2

The electric field is perpendicular to the direction of propagation of the wave.

The magnetic field is perpendicular to the direction of propagation of the wave.

In other words both the electric and magnetic fields are perpendicular to the propagation of the wave.

But in the perpendicular plane to the direction of the propagation of the wave, the electric field and magneticfield are perpendicular to each other. The angle between them is 90 degree.

But at any time if the electric field is maximum then the magnetic field is also maximum.

If the electric field is zero then the magnetic field is also zero.

If we view the fields in the direction of the wave, if the electric field oscillated vertically up and down, then the magnetc field will be oscillating from left to right.

When the electric field has the maximum (up) amplitude, then the magnetic field will have (left) the maximum amplitude.

When the electric field returns to zero; the magnetic field returns to zero.

When the electrric field goes down to the maximum.the magnetic field goes to the right extreame.

This process continues. Hence both fields are in phase with each other. But both fields are directed 90 degre to each other.


Further, for studying the behaviour of em wave,it is enough if one consider either one of the field. It is because if one is the cause the other one is the result.

Answer 3

A magnet field exists around electrons that are moving therefore static electricity has no magnetic field. That's why a permanent magnet has no electricity unless you move it.