EM Field vs EM Wave: Understanding Distance & Strength Differences

[spacebear2000]

Why does the strength of an electrical field diminish with distance from its source whereas the amplitude and frequency of a beam of light do not vary, regardless of distance?

 

[kote]

Why does the strength of an electrical field diminish with distance from its source whereas the amplitude and frequency of a beam of light do not vary, regardless of distance?

Spacebear, one way to think of it is that even though the individual photons may not lose energy, they are more spread out as you move farther from a source - you have fewer and fewer photons interacting with whatever it is you are using to measure the strength.

The flux or intensity can tell you how much spreading out has occurred and how much relative "strength" you have left at any region.