Radio waves of constant amplitude are produced by a/an . . . . . . .

$A$ $25\, m$ long antenna is mounted on an antenna tower. The height of the antenna tower is $75\, m$. The wavelength (in meter) of the signal transmitted by this antenna would be

$A$ sinusoidal carrier voltage is amplitude modulated. The resultant amplitude modulated wave has maximum and minimum amplitude of $120 \, V$ and $80 \, V$ respectively. The amplitude of each sideband is $.......... \, V$.

$A$ $TV$ transmitting antenna is $128 \ m$ tall. If the receiving antenna is at the ground level,the maximum distance between them for satisfactory communication in line-of-sight mode is (radius of the earth $R_e = 6.4 \times 10^6 \ m$):

In $AM$ modulation,a signal is modulated on a carrier wave such that maximum and minimum amplitude are found to be $6\,V$ and $2\,V$ respectively. The modulation index is $\dots \%$.

If the highest modulating frequency of the wave is $5 kHz$,then the number of stations that can be accommodated in a $150 kHz$ bandwidth is