In the process of modulation,........

$A$ transmitter transmits a power of $10\, kW$ when modulation is $50\%$. The power of the carrier wave is.......$kW$.

$A$ signal $A \cos \omega t$ is transmitted using $v_0 \sin \omega_0 t$ as a carrier wave. The correct amplitude modulated $(AM)$ signal is:

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 $....$

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:

Which characteristic of a carrier light wave is modulated for the modulation of a light wave?