$A$ carrier wave of peak voltage $15 \,V$ is used to transmit a message signal. If the modulation index is $60 \%$, then the peak voltage of the modulating signal is (in $\,V$)

For efficient transmission of sound waves of wavelength $\lambda$,the minimum length of the antenna should be.....

$A$ $TV$ tower has a height of $100 \ m$. The average population density around the tower is $1000 \ \text{per} \ km^2$. The radius of the earth is $6.4 \times 10^6 \ m$. The population covered by the tower is:

$A$ message signal of frequency $14 kHz$ is used to modulate a carrier of frequency $900 kHz$. The frequencies of the sidebands are:

The wavelength of the carrier waves in a modern optical fiber communication network is close to ........ $nm$.

In an amplitude modulated wave for an audio frequency of $500 \, \text{cycles/second}$, the appropriate carrier frequency will be ........ $\text{cycles/second}$.