^Generating EM waves

^Generating EM waves

Maxwell suggested an accelerating charge produces EM waves. An electric charge oscillating harmonically with time produces an oscillating electric field in its neighbourhood & this field in turn produces an oscillating magnetic in the neighbourhood. The process continues because the oscillating electric and magnetic fields act as sources of each other & hence an EM wave originates from the oscillating charge. The frequency of the EM wave is equal to the frequency of oscillation of the charge. The energy carried by the wave comes from the source which makes the charge oscillating. To generate an EM wave of frequency f, we need to set up an ac circuit in which the current oscillates at the frequency f. It is easier to generate low frequency EM waves such as a radio wave than to produce high frequency EM waves. e.g. the generation of yellow light requires an oscillator of frequency 6 x 10¹⁴ Hz, while the modern oscillators have frequency not above 10¹¹ Hz.