$A$ message signal of frequency $5\,kHz$ is used to modulate a carrier signal of frequency $2\,MHz$. The bandwidth for amplitude modulation is $..........\,kHz$.

$A$ $TV$ transmission tower antenna is at a height of $20\, m$. Suppose that the receiving antenna is at:
$(i)$ ground level
$(ii)$ a height of $5\, m$.
The increase in antenna range in case $(ii)$ relative to case $(i)$ is $n\%$.
The value of $n$,to the nearest integer,is .....$\%$

An amplitude modulated wave is represented by $c_m(t)= 10[1+0.6 \sin (1250 t)] \sin (10^8 t)$. Then the modulation index is

We do not transmit low frequency signals to long distances because:
$(a)$ The size of the antenna should be comparable to signal wavelength,which is impractical for a signal of longer wavelength.
$(b)$ Effective power radiated by a long wavelength baseband signal would be high.
$(c)$ We want to avoid mixing up signals transmitted by different transmitters simultaneously.
$(d)$ Low frequency signals can be sent to long distances by superimposing them with a high frequency wave.
Therefore,the most suitable options are:

An $AM$ wave has $1800 \ W$ of total power content. For $100 \%$ modulation,the carrier should have a power content equal to $...... \ W$.

Which type of propagation is used to transmit radio waves from one place to another?