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(C) Sound waves are low-frequency waves (typically $20 \ Hz$ to $20 \ kHz$). For efficient transmission of electromagnetic waves,the antenna length sh

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They are heavily absorbed by the atmosphere.

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(C) Sound waves are low-frequency waves (typically $20 \ Hz$ to $20 \ kHz$). For efficient transmission of electromagnetic waves,the antenna length should be at least $\lambda/4$,where $\lambda$ is the wavelength. For a frequency of $15 \ kHz$,the wavelength $\lambda = c/f = (3 	imes 10^8 \ m/s) / (15 	imes 10^3 \ Hz) = 20 \ km$. The required antenna height would be $\lambda/4 = 5 \ km$,which is practically impossible to construct. Furthermore,low-frequency waves are heavily absorbed by the atmosphere. Therefore,sound waves are modulated onto high-frequency carrier waves for transmission.

$A$. Optical Fiber Communication	$P$. Ultrasound
$B$. Radar	$Q$. Infrared Light
$C$. Sonar	$R$. Microwaves
$D$. Mobile Phones	$S$. Radio Waves

List $I$	List $II$
$A$. Attenuation	$I$. Combination of a receiver and transmitter.
$B$. Transducer	$II$. Process of retrieval of information from the carrier wave at receiver.
$C$. Demodulation	$III$. Converts one form of energy into another.
$D$. Repeater	$IV$. Loss of strength of a signal while propagating through a medium.

Sound waves cannot be transmitted directly after conversion into electrical waves because...

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