Flashcards

Fluorescence - Physics

Finnuala Brett English 4 cards 1,676 views

Cards in this deck (4)

1Q: 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.
2ii) 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.
3iii) 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.
4iv) 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.