Given below are some famous numbers associated with electromagnetic radiations in different contexts in physics. State the part of the electromagnetic spectrum to which each belongs.
(a) 21 \mathrm{~cm} (wavelength emitted by atomic hydrogen in interstellar space).
(b) 1057 \mathrm{MHz} (frequency of radiation arising from two close energy levels in hydrogen; known as Lamb shift).
Given below are some famous numbers associated with electromagnetic radiations in different contexts in physics. State the part of the electromagnetic spectrum to which each belongs.
(a) 21 \mathrm{~cm} (wavelength emitted by atomic hydrogen in interstellar space).
(b) 1057 \mathrm{MHz} (frequency of radiation arising from two close energy levels in hydrogen; known as Lamb shift).

(a) Radio waves

(b) Radio waves