An antenna is mounted on a $400 \; m$ tall building. What will be the wavelength of the signal that can be radiated effectively by the transmission tower up to a range of $44 \; km$? (In $m$)

$A$ message signal of frequency $8 \text{ kHz}$ and peak voltage $12 \text{ V}$ is used to modulate a carrier of frequency $1.2 \text{ MHz}$ and peak voltage $20 \text{ V}$. The modulation index is

If the frequencies of the carrier wave and message signal are $1 \text{ MHz}$ and $28 \text{ kHz}$ respectively,then the frequencies of the side bands are

In a communication system,the range for line-of-sight propagation on Earth is $d$ for an antenna height of $h$. If $h$ is doubled,then the new range is:

In an amplitude modulator circuit,the carrier wave is given by $C(t) = 4 \sin(20000 \pi t)$ and the modulating signal is given by $m(t) = 2 \sin(2000 \pi t)$. The values of the modulation index and the lower sideband frequency are:

$A$ carrier wave of peak voltage $12 \,V$ is used to transmit a signal. If the modulation index is $75 \%$, the peak voltage of the modulating signal is (in $\,V$)