. How are electromagnetic waves produced


Best Answer

Neither stationary charges nor charges in uniform motion (steady currents) can be sources of electromagnetic waves.  The former produces only electrostatic fields, while the latter also produces magnetic fields that however, do not vary with time.  It is an important result of Maxwell’s theory that accelerated charges radiate electromagnetic waves.

Consider a charge oscillating with some frequency. This produces an oscillating electric field in a space which produces an oscillating magnetic field which in turn is a source of oscillating electric field and so on. The oscillating electric and magnetic fields thus regenerate each other, so to speak, as the wave propagates through the space. The frequency of electromagnetic wave naturally equals the frequency of oscillation of the charge.  The energy associated with the propagating wave comes at the expense of energy of the source – the accelerated charge. 

 

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