Question

(a) "EM wavelength correlates with the size of the radiating system." Give two examples.
(i) Why do long-distance radio broadcasts use shortwave bands?
(ii) Why are X-ray telescopes satellite-based, while optical/radio telescopes are ground-based?

Hint:

(a) Antenna size and atomic size. (b) Ionospheric reflection and atmospheric absorption.

Answer 1

(a) 1. The length of a radio transmitter antenna is approximately equal to the radio wavelength. 2. The wavelength of visible light is roughly the size of the atoms or molecules emitting it. (b) (i) Shortwave radio signals are reflected by the ionosphere, facilitating communication over extended distances. (ii) X-rays are absorbed by the Earth's atmosphere, whereas optical and radio waves are not.