An antenna of length $3 \ m$ will effectively radiate which frequency?

Consider the following statements regarding satellite communication:
$1$. Frequencies between $1.5 \text{ MHz}$ and $1 \text{ MHz}$ are used in satellite communication.
$2$. The frequencies for uplink and downlink are different.
$3$. The orbit of a geostationary satellite makes an angle of $0^{\circ}$ with the equatorial plane of the Earth.
Which of the above statements are correct?

The amplitude of $15 \sin (1000 \pi t)$ is modulated by $10 \sin (4 \pi t)$ signal. The amplitude modulated signal contains frequency(ies) of
$A) 500 \text{ Hz}$
$B) 2 \text{ Hz}$
$C) 250 \text{ Hz}$
$D) 498 \text{ Hz}$
$E) 502 \text{ Hz}$
Choose the correct answer from the options given below:

The bit rate for a signal,which has a sampling rate of $8 \, kHz$ and where $16$ quantisation levels have been used,is ......... $bits/sec$.

Which device is used to convert one form of energy into another?

The modulation index of an $FM$ carrier having a carrier swing of $200\, kHz$ and a modulating signal frequency of $10\, kHz$ is: