Question

Given below are some famous numbers associated with electromagnetic radiation in different contexts in physics. State the part of electromagnetic spectrum to which each belongs to

(i) 21 cm (wavelength emitted by atomic hydrogen in interstellor space). 

(ii) 1057 Hz (frequency of radiation arising from two close energy levels in hydrogens known as lamb shift). 

(iii) 2.7 K (temperature associated with isotropic radiation filling all space thought to be a relic of the big bang origin of the universe). 

(iv) 5890 Å and 5896 Å (double lines of sodium). 

(v) 14.4 KeV (energy of a particular transition in Fe⁵⁶ nucleous associated with a famous high resolution spectroscopic method – Mossbauer spectroscopy).

Answer 1

(i) Given wave length corresponds to short wavelength radio-waves. 

(ii) High frequency end of radio waves (short radio waves).

(iii) T = 2.7 K gives λ = 0.29 cm/T = = 0.11 cm, which corresponds to microwave region.

(iv) D₁ and D₂ lines in the visible region (yellow).

(v) Given E = 14.4 KeV = 14.4 x 10³ x 1.6 x 10^-19 J

Which lies high frequency x–rays or soft γ–ray region.