$A$ signal of frequency $3 \text{ kHz}$ is amplitude modulated on a carrier wave of frequency $2.5 \text{ MHz}$. The upper and lower sideband frequencies in the resultant signal are

The height of a transmitting antenna is $h \ m$ and the height of a receiving antenna is $45 \ m$. The distance between them is $40 \ km$. For satisfactory $Line\, of\, Sight$ $(LOS)$ communication between the two antennas,the height of the transmitting antenna $h$ must be ....... $m$. (Radius of the Earth $R = 6400 \ km$)

The maximum distance between the transmitting and receiving antennas for satisfactory communication in line of sight mode is $57.6 \ km$. If the height of the receiving antenna is $80 \ m$,the height of the transmitting antenna is (Radius of earth $= 6.4 \times 10^6 \ m$) (in $m$)

For short-distance communication,waves with a frequency of $f$ $MHz$ are reflected back from the ionosphere. If the electron density of the ionosphere is $10^{11} \ m^{-3}$,what is the value of $f$?

The mathematical form of an $AM$ wave is given by $e = 50 (1 + 0.5 \sin(2\pi \times 5 \times 10^3 t)) \sin(31.4 \times 10^6 t) \text{ V}$. The frequencies of the $LSB$ and $USB$ in the given $AM$ wave are,respectively,....... and ....... .

The total maximum transmitted power in amplitude modulation if the carrier output power is $1 \ kW$ is