The radius of the Earth is $6400 \text{ km}$. If the height of the antenna is $500 \text{ m}$, then its range is: (in $\text{ km}$)

$A$ transmitting antenna is at a height of $50 \ m$ and the receiving antenna is at a height of $5 \ m$. What is the maximum communication range in $km$? (Take $R = 6400 \ km$)

To radiate a wave of frequency $1 \text{ kHz}$ efficiently,what should be the minimum length of the antenna in $km$?

The modulation index for an $A.M.$ wave having maximum and minimum peak-to-peak voltages of $14\,mV$ and $6\,mV$ respectively is:

In a communication system,the range for line-of-sight propagation on Earth is $d$ for an antenna height of $h$. If $h$ is doubled,then the new range is:

If modulation index $\mu = \frac{1}{2}$ and $V_{m} = 2$,then $V_{c} = \, ?$