NCERT Solutions for Chapter: Electromagnetic Waves, Exercise 2: ADDITIONAL EXERCISES

Given here are some famous numbers associated with electromagnetic radiations in different contexts in physics. State the part of the electromagnetic spectrum to which each belongs, $5890\mathrm{}\mathrm{\AA }\mathrm{}-\mathrm{}5896\mathrm{}\mathrm{\AA }$ [double lines of sodium].

Given here is some famous number associated with electromagnetic radiations in different contexts in physics. State the part of the electromagnetic spectrum to which it belongs,$14.4 \mathrm{keV}$ [energy of a particular transition in ${}^{\text{57}}\text{Fe}$ nucleus associated with a famous high-resolution spectroscopic method (Mossbauer spectroscopy)]. 
 

Answer the following question: Long distance radio broadcasts use short - wave bands. Why? 

It is necessary to use satellites for long distance TV transmission. Why?

Optical and radio telescopes are built on the ground, but X-ray astronomy is possible only from satellites orbiting the earth. Why?

The small ozone layer on top of the stratosphere is crucial for human survival. Why?

If the earth did not have an atmosphere, would its average surface temperature be higher or lower than what it is now?

Some scientists have already predicted that a global nuclear war on the earth would be followed by a severe ‘nuclear winter’ with a bad effect on life on earth. What might be the basis of this prediction?