# Q&A - Ask Doubts and Get Answers

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The use of nuclear weapons would cause the formation of smoke clouds preventing the light from the sun reaching earth surface and it will also deplete the atmosphere and therefore stopping the greenhouse effect and thus doubling the cooling effect.
If the earth did not have an atmosphere its average surface temperature be lower than what it is now as in the absence of atmosphere there would be no greenhouse effect.
The small ozone layer on top of the stratosphere is crucial for human survival as it absorbs the ultraviolet radiations coming from the sun which are very harmful to humans.
X-rays are absorbed by the atmosphere and therefore the source of X-rays must lie outside the atmosphere to carry out X-ray astronomy and therefore satellites orbiting the earth are necessary but radio waves and visible light can penetrate through the atmosphere and therefore optical and radio telescopes can be built on the ground.
As TV signals are of high frequencies they are not reflected by the ionosphere and therefore satellites are to be used to reflect them.
Long distance radio broadcasts use short-wave bands as these are refracted by the ionosphere.
E=14.4 keV Wavelength() =  = = 0.85 A0 X-rays
Visible light.
Using formula,  = 0.107cm Micro waves.
Frequency()=1057 MHz Wavelength()  =0.283 m =28.3 cm Radio waves