In the process of modulation,the audio waves are called ...........

In an $AM$ wave,the carrier power is given by:

$A$ $100\, V$ carrier wave is made to vary between $160\, V$ and $40\, V$ by a modulating signal. What is the modulation index?

Ground waves are polarized in which direction?

For $VHF$ signal broadcasting,what is the maximum service area in $km^{2}$ that will be covered by an antenna tower of height $30\, m$,if the receiving antenna is placed at the ground? Let the radius of the earth be $6400\, km$. (Round off to the nearest integer) (Take $\pi$ as $3.14$)

Which waves can be transmitted more efficiently by an antenna?