Electromagnetic Waves - Implications

Electromagnetic Waves


































From the laws which govern the motion of electric charges, Maxwell deduced a speed.

c = 3 x 10^8 m/s
The speed of electromagnetic waves is itself a physical law!


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In 1888, Heinrich Hertz demonstrated the production and detection of electromagnetic waves using spark gaps --- the first radio.

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An electric or magnetic field tells you what would happen if there were a charged particle present.

The fields and the waves are present even if there are no charged particles present!

Electromagnetic waves are waves in a "what would happen if" abstraction! --- waves in nothing!


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The speed which Maxwell predicted was already familiar to scientists.

In 1676, Olaf Roemer had noticed peculiar delays in the apparent orbits of Jupiter's Moons and calculated the speed of light to be close to m/s.

--- light (and several other types of radiation) must be an electromagnetic wave.

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