I was reading about antennas and I found an statement somewhat like this "loop antennas are more efficient compared to other antennas when close to the human body since the human body interacts more with the electric field than with the magnetic field of light and loop antennas interact more with the light magnetic field instead of the light electric field like most antennas."

So that left me wondering: if I have a beam or a wave of light and I decrease the amplitude of its electric field should not the magnetic field amplitude decrease in the same proportion as well? after all the way light propagates is(according to my knowledge) by electric and magnetic fields propagating one another through the space... By the way I do not study physics.


1 Answer 1


Nowadays we are talking about an EM field. The electric and magnetic components are observer dependent, one observer could view the same field as electric and another as magnetic.

You are asking whether the electric and magnetic fields can exist independently.

Now, we are talking about near and far fields.

In the far-field region, each part of the EM field (electric and magnetic) is "produced by" (or associated with) a change in the other part, and the ratio of electric and magnetic field intensities is simply the wave impedance. However, in the near-field region, the electric and magnetic fields can exist independently of each other, and one type of field can dominate the other.

In the near field region, the answer is yes, they can exist independently.


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