Name the three different modes of propagation of electromagnetic waves. Explain, using a proper diagram the mode of propagation used in the frequency range above 40 MHz.

The mode of propagation used by short wave broadcast services is

The mode of propagation used by short wave broadcast services is

The ultra high frequency band of radiowaves in electromagnetic wave is used as in

Give the range of wavelength of the electromagnetic waves visible to us.

Write the range of frequencies of electromagnetic waves which propagate through sky wave mode.

Define the term critical frequency in relation to sky wave propagation of electromagnetic waves.

Name the electromagnetic waves used for studying crystal structure of solids. What is its frequency range?

Which mode of propagation is used by short wave broadcast services ?.

What is sky wave communication Why is this mode of propagation restriced to the frequenceies only upto few MHz?

Distinguish between 'sky waves' and 'space waves' modes of propagation in communication system. (a) Why is sky wave mode propagation restricted to frequencies upto 40 MHz?