Answer the following questions: (a) Long distance radio broadcasts use short-wave bands. Why? (b) It is necessary to use satellites for long distance TV transmission. Why? (c) Optical and radiotelescopes are built on the ground but X-ray astronomy is possible only from satellites orbiting the earth. Why? (d) The small ozone layer on top of the stratosphere is crucial for human survival. Why? (e) If the earth did not have an atmosphere, would its average surface temperature be higher or lower than what it is now? (f ) Some scientists have predicted that a global nuclear war on the earth would be followed by a severe ‘nuclear winter’ with a devastating effect on life on earth. What might be the basis of this prediction?
Answers
Answer:
a) Refraction of only shortwave band by ionosphere is the reason thay long distance radio broadcasts use shortwave bands.
b) Television signal which have high frequencies and energies are not reflected by ionosphere.
Satellite helps in reflecting TV signals.
c) X-ray astronomy is possible only with the help of satellite orbiting the earth because atmosphere absorbs x-ray, but can be penetrated by visible and radio waves.
Hence radiotelescopes and optical are built on ground.
d) Ozone layer absorbs harmful ultraviolet radiation of sun and hence helps in the survival of human.
e) If there were no atmosphere, there would have been no greenhouse effect and hence temperature would have dropped rapidly.
f)Dire consequences like depletion of ozone layer, formation of smoky cloud and thus preventing penetration of sunlight.
Explanation: