For $100\%$ modulation,what should be the value of the minimum amplitude $(E_{min})$ of the modulated wave?

In amplitude modulation,the amplitude of the carrier wave is $10 \ V$ and the amplitude of one of the sidebands is $2 \ V$. Then the modulation index is

$A$ carrier wave $v_{c}(t) = 160 \sin(2 \pi \times 10^{6} t) \text{ V}$ is made to vary between $V_{\max} = 200 \text{ V}$ and $V_{\min} = 120 \text{ V}$ by a message signal $v_{m}(t) = A_{m} \sin(2 \pi \times 10^{3} t) \text{ V}$. The peak voltage $A_{m}$ of the modulating signal is ..... .

If multiple waves with modulation indices $n_1, n_2, n_3, ...$ modulate a carrier wave,what is the total modulation index of the resulting wave?

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

If a carrier wave $C(t) = A \sin \omega_c t$ is amplitude modulated by a modulating signal $m(t) = A \sin \omega_m t$,then the equation of the modulated signal $[C_m(t)]$ and its modulation index are respectively: