Audio signals cannot be transmitted directly | vedclass

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Question

(D) Audio signals have very low frequencies (typically $20 \ Hz$ to $20 \ kHz$).The length of the antenna $(L)$ must be of the order of the wavelength

Vedclass · Accepted Answer

The required length of the transmitting antenna is too large,which is not practically feasible.

Vedclass · Answer

(D) Audio signals have very low frequencies (typically $20 \ Hz$ to $20 \ kHz$).The length of the antenna $(L)$ must be of the order of the wavelength $(\lambda)$ of the signal,i.e.,$L \approx \lambda / 4$.The wavelength is given by $\lambda = c / f$,where $c$ is the speed of light $(3 	imes 10^8 \ m/s)$.If we take a frequency of $15 \ kHz$,then $\lambda = (3 	imes 10^8) / (15 	imes 10^3) = 20,000 \ m = 20 \ km$.Therefore,the required antenna length would be $L = 20,000 / 4 = 5,000 \ m = 5 \ km$.Constructing an antenna of such a large length is not practically feasible,hence audio signals cannot be transmitted directly.

Audio signals cannot be transmitted directly because $.......$

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