Electromagnetic Spectrum:The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation, including radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays.
Quantum Mechanics:Quantum mechanics is the branch of physics that deals with the behavior of matter and energy on the atomic and subatomic scale, including the nature and behavior of atoms, molecules, and photons.
Atomic Emission Spectrum: The atomic emission spectrum is the series of discrete frequencies of electromagnetic radiation emitted by an atom when its electrons transition from higher to lower energy levels.