Tuesday, April 21, 2015

electromagnetism - How electromagnetic fields travel through vacuum?


How electromagnetic fields travel through vacuum is it right to say that they propagate or travel? do they alternately form each other by charged particles?



Answer




from a, b and c:


An electromagnetic field is propagating by changing the field that's generated by electrically charged particles pass through the air and the space that is devoid of particles of space.



An electromagnetic wave propagates, not an electromagnetic field. An EM wave is a propagating disturbance in the existing electromagnetic field.



Consider the field of an isolated charged point particle - the field extends over all space.


Should the particle abruptly accelerate for some short time, the disturbance in the electromagnetic field of the particle will propagate 'to infinity' at the speed $c$.


From the classic textbook "Gravitation":


enter image description here


For an animated visualization, try the Java applet here.


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