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?
a)
Long distance radio broadcasts uses short wave bands because only these can be reflected from ionosphere (electrically charged layer of upper atmosphere). This phenomenon of refraction of EM waves back towards earth is called sky wave.
b)
The satellites are used for long distance TV transmission because it requires signals of high frequencies and high energy which are not reflected by the ionosphere layer of atmosphere.
c)
There are two types of telescope available on earth 1) radio telescope 2) optical telescope because visible and radio wave of EM radiation can penetrate the atmosphere and reach the surface of earth. X-ray have wavelength of 0.01 nm to 10 nm penetrate the atmosphere and hence can be possible only from satellites orbiting the earth.
d)
The ozone layer is the topmost layer ranging from 11 − 50 km in the atmosphere and is crucial for the survival of the mankind because it reflects back the harmful UV rays coming from sun thus preventing it reaching the Earth surface.
e)
The atmosphere of the Earth is one of the many causes which make the life possible on the planet. The atmosphere contains various gases which is required for the plants and humans to exist. The ozone layer reflects back the harmful UV rays. The atmosphere is also responsible for the regulation of temperature on Earth it maintains average temperature which otherwise could have fall below freezing point or over heat.
f)
Nuclear war will lead to the production of large amount of gases which accumulates in the atmosphere and persist over a longer time period.Thses gases will form cloud just like smog and prevent Sun rays to reach the Earth surface and this will lead to the death of plants and depletion of ozone layer. Post nuclear effects are always catastrophic.
a)
Long distance radio broadcasts uses short wave bands because only these can be reflected from ionosphere (electrically charged layer of upper atmosphere). This phenomenon of refraction of EM waves back towards earth is called sky wave.
b)
The satellites are used for long distance TV transmission because it requires signals of high frequencies and high energy which are not reflected by the ionosphere layer of atmosphere.
c)
There are two types of telescope available on earth 1) radio telescope 2) optical telescope because visible and radio wave of EM radiation can penetrate the atmosphere and reach the surface of earth. X-ray have wavelength of
d)
The ozone layer is the topmost layer ranging from
e)
The atmosphere of the Earth is one of the many causes which make the life possible on the planet. The atmosphere contains various gases which is required for the plants and humans to exist. The ozone layer reflects back the harmful
f)
Nuclear war will lead to the production of large amount of gases which accumulates in the atmosphere and persist over a longer time period.Thses gases will form cloud just like smog and prevent Sun rays to reach the Earth surface and this will lead to the death of plants and depletion of ozone layer. Post nuclear effects are always catastrophic.
