Fluorescence - Physics

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The mercury atoms in a fluorescent tube...
Finnuala Brett
Flashcards by Finnuala Brett, updated more than 1 year ago
Finnuala Brett
Created by Finnuala Brett over 6 years ago
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Q: The mercury atoms in a fluorescent tube are excited and then emit photons in the ultraviolet region of the electromagnetic spectrum. i) Explain how the mercury atoms become excited. A: i) The kinetic energy of the electrons passing through the tube transfers energy to the electrons in mercury atoms when colliding. This causes the orbital electrons to move to a higher energy level.
ii) Explain how the excited mercury atoms emit photons. ii) As the electrons become de-excited they emit photons equal to the energy difference between the levels.
iii) Why do the excited mercury atoms emit photons of characteristic frequencies? iii) Atoms have discrete energy levels; when electrons change levels they lose a discrete amount of energy. This means that photons of discrete frequencies are emitted.
iv) Explain how the coating on the inside of a fluorescent tube emits visible light. iv) The coating absorbs photons and re-emits photons of lower energy.
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