Mention three different modes of propagation used in communications system. Explain with the help of a diagram how long distance communication can be achieved by ionospheric reflection of radio waves?

Distinguish between Sky wave and Space wave modes of propagation in a communication system.

Which mode of propagation is used by short wave broadcast services having frequency range from a few MHz upto 30 MHz ? Explain diagrammatically how long distance communication can be achieved by this mode . Why is there an upper limit to frequency of waves used in this mode ?

With the help of circuit diagram, explain how a meter bridge can be used to find unknown resistance of a given wire?

A : Long distance radio broadcasts use short-wave bands. R : Ionosphere reflectes waves in these bands.

Two waves A and B of frequencies 2MHz and 3 MHz, respectively are beamed in the same direction for communication via sky wave. Which one of these is likely to travel longer distance in the ionosphere before suffering total internal reflection?