The antenna current of an $AM$ transmitter is $8 \ A$ when only the carrier is sent,but it increases to $8.96 \ A$ when the carrier is modulated by a sine wave. The percentage of modulation is: (in $\%$)

An optical fibre communication system works on a wavelength of $1.3 \mu m$. The number of subscribers it can feed if a channel requires $20 \ kHz$ is:

An amplitude modulated wave is modulated to $50\%$. If the carrier and one of the sidebands are suppressed,the percentage reduction in power is ....$\%$

In amplitude modulation,the message signal $V_{m}(t) = 10 \sin(2 \pi \times 10^{5} t) \text{ V}$ and the carrier signal $V_{c}(t) = 20 \sin(2 \pi \times 10^{7} t) \text{ V}$. The modulated signal contains the message signal with lower sideband and upper sideband frequencies. Therefore,the bandwidth of the modulated signal is $\alpha \text{ kHz}$. The value of $\alpha$ is:

$A$ message signal of $3 \text{ kHz}$ is used to modulate a carrier signal of frequency $1 \text{ MHz}$ using amplitude modulation. The upper sideband frequency and bandwidth respectively are:

$A$ message signal of frequency $50 / \pi \text{ kHz}$ and peak voltage of $5 \text{ V}$ is used to modulate a carrier of frequency $1 \text{ MHz}$ and peak voltage $20 \text{ V}$. The modulation index is