An amplitude modulated wave is represented by $10[1+0.6 \sin(40 \times 10^3 t)] \sin(4 \times 10^6 t)$ volt,where $t$ is in seconds. The ratio of the upper sideband frequency to the lower sideband frequency is:

An antenna is placed in a dielectric medium of dielectric constant $6.25$. If the maximum size of the antenna is $5.0 \, mm$,what is the minimum frequency of the signal it can radiate in $GHz$? (Given $\mu_{r} = 1$ for the dielectric medium)

$A$ telephonic communication service is working at a carrier frequency of $20 GHz$. Only $20 \%$ of it is utilized for transmission. If each channel requires a bandwidth of $5 kHz$,then the number of telephonic channels that can be transmitted simultaneously are

The range of frequency bands used for standard $AM$ broadcast is

$A$ receiving station on the ground is receiving a signal of frequency $5 \ MHz$ from a transmitter. Then the signal can come via

The maximum and minimum voltage of an amplitude modulated signal are $60\,V$ and $20\,V$ respectively. The percentage modulation index will be $....\%$