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Electromagnetic
Waves |
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According to Maxwell, a changing magnetic field produce a changing
electric field. The changing electric field in turn produces
a changing magnetic field and so on. In fact ,the two field
act as the sources of each other. Therefore, in order to initiate
an electromagnetic wave, we must create a changing electric field
.Once we do this, the self regenerating process occurs and the
electromagnetic wave propagates of its own. |
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We create changing fields when we alter the motion of electric
charge i.e. we create changing fields when we alter the motion
of electric charge i.e. we accelerate the charge.- Accelerated
electric charge is the source of electromagnetic waves. |
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(I) In an LC circuit, the charge oscillate (i.e. undergoing
acceleration) across the capacitor plates. Therefore, an Lc
circuit emits electromagnetic waves which have the same frequency
as that of the oscillating charge. |
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(II)
The emission of visible light is associated with electrons
jumping from higher energy orbit to lower energy orbit. |
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(III) X-rays are produced when fast moving electrons abruptly
decelerate as they collide with a metal target of high atomic
number. |
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All electromagnetic waves are similar except for their wavelength
and frequency but this difference is very important. For
example, visible
light is one kind of EM wave having frequency order of 1014Hz.It
is not possible to generate light wave using electronic
circuits.
What about the electromagnetic waves whose frequencies lie
above and below the visible range? Such electromagnetic waves
are invisible and can be ducted or measured by physical means. |
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