An antenna behaves as a resonant circuit only when its length is

$A$ $100\,m$ long antenna is mounted on a $500\,m$ tall building. The complex can become a transmission tower for waves with $\lambda$ (approx) ........ $m$.

$A$ person tries to broadcast with the same antenna both the signals at $10^7 \,Hz$ and $10^6 \,Hz$. If the receiver at some distance has to receive an equal strength for both the frequencies, then the broadcaster has to approximately increase the signal strength at $10^6 \,Hz$ to $10^7 \,Hz$ by

The amplitude of the upper and lower sidebands of an $A.M.$ wave,where a carrier signal with frequency $11.21 \, MHz$ and peak voltage $15 \, V$ is amplitude modulated by a $7.7 \, kHz$ sine wave of $5 \, V$ amplitude,are $\frac{a}{10} \, V$ and $\frac{b}{10} \, V$ respectively. Then the value of $\frac{a}{b}$ is $....$

The height of a $TV$ transmitter antenna is $100 \ m$. What is the area covered by the transmitter for broadcasting? $(R = 6.4 \times 10^{6} \ m)$

The total maximum transmitted power in amplitude modulation if the carrier output power is $1 \ kW$ is