If the sum of the heights of transmitting and receiving antennas in the line of sight of communication is fixed at 160 m, then the maximum range of LOS communication is ___________ km. (Take radius of Earth = 6400 km)

A square shaped wire with resistance of each side 3$$\Omega$$ is bent to form a complete circle. The resistance between two diametrically opposite points of the circle in unit of $$\Omega$$ will be ___________.

A wire having a linear mass density 9.0 $$\times$$ 10^$$-$$4 kg/m is stretched between two rigid supports with a tension of 900 N. The wire resonates at a frequency of 500 Hz. The next higher frequency at which the same wire resonates is 550 Hz. The length of the wire is ____________ m.

The voltage drop across 15$$\Omega$$ resistance in the given figure will be ______________ V.