Radio waves that reach the receiver after being reflected from the ionosphere propagate via .......

$A$ 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 $\,V$)

In the given detector circuit,the suitable value of carrier frequency is

An amplitude modulated wave is represented by the expression $v_{m}=5(1+0.6 \cos 6280 t) \sin (211 \times 10^{4} t) \; V$. The minimum and maximum amplitudes of the amplitude modulated wave are,respectively:

The frequency range suitable for beyond-the-horizon communication using sky waves is:

$A$ $TV$ transmission tower has a height of $140\, m$ and the height of the receiving antenna is $40\, m$. What is the maximum distance up to which signals can be broadcasted from this tower in $LOS$ (Line of Sight) mode? (Given: radius of earth $R = 6.4 \times 10^6\, m$)