The Total solution for NCERT class 6-12
Given below are some famousnumbers associated with electromagnetic radiations in different contexts inphysics. State the part of the electromagnetic spectrum to which each belongs.
(a) 21 cm (wavelength emitted byatomic hydrogen in interstellar space).
(b) 1057 MHz (frequency of radiationarising from two close energy levels in hydrogen; known as Lamb shift).
(c) 2.7 K [temperature associatedwith the isotropic radiation filling all space-thought to be a relic of the‘big-bang’ origin of the universe].
(d) 5890 Å - 5896 Å [double lines ofsodium]
(a) Radiowaves; it belongs to the short wavelength end of the electromagnetic spectrum.
(b) Radio waves; it belongs to the shortwavelength end.
(c) Temperature, T =2.7 °K
This wavelength corresponds tomicrowaves.
(d) This is the yellow light of the visiblespectrum.
(e) Transition energy is given by therelation,
E = hν
Where,
h = Planck’s constant = 6.6× 10−34 Js
ν =Frequency of radiation
Energy, E = 14.4 K eV
This corresponds to X-rays.