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Q & A: electromagnetic waves

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Most recent answer: 06/19/2013
Q:
Electric fields and magnetic fields are made of photons. According to De Broglie's postulation, moving particles of matter exhibit wave feature with certain associated wavelength.The photo-electric effect also validates the dual nature of particles like photons and other sub-atomic particles. As electric fields and magnetic fields are made of photons, do they also exhibit wave like properties? Electric field emanated from any charge does travel sinusoidally?
- Pritesh Rajput (age 18)
Varanasi, UP, India
A:

Certainly there are electromagnetic waves. They were predicted by Maxwell as solutions to his equations in about 1864. These equations involve purely classical electromagnetism, with no quantum elements. The quantized version predicts some behavior not present in the classical waves, but the general wave picture was already there. In fact, it was these same properties of Maxwell's equations that inspired Einstein to develop special relativity, which helped to trigger the quantum theory.

Neither electromagnetic waves nor any other type need to travel sinusoidally. The sinusoidal form is just a convenient one for mathematical descriptions. It has the special property of keeping its shape as waves travel in a medium with a frequency-dependent response. In a vacuum, however, you could make up any shape of plane wave and it would keep its shape as the whole thing moved at the same speed, c. 

Mike W.


(published on 06/19/2013)

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