The humble fluorescent light truly is a thing of wonder. As you awaken it from its heavy slumber it blushes with a flicker and a spark, accompanied by the soothing sound of someone twanging a thin piece of metal repeatedly.
You may have often wondered, as indeed I have, how a fluorescent light actually functions. I am sure that this is amongst the greatest problems to ever burden mankind. Well, my friends, fret no further, for today I will be revealing the ancient secrets behind the fluorescent lamp. Go get yourself a glass of milk or something, because you’re in for a hell of an intellectual ride.
First discovered in the wild by Thomas Edison in 1896, the modern fluorescent lamp is essentially a glass tube filled with mercury vapour and coated inside with fluorescent materials called phosphors. When the light is switched on, electrons flow from the cathode end of the tube to the anode end (positive to negative). If an electron collides with a mercury atom, some of the electron’s kinetic energy may be transferred from the electron to the mercury atom.
Provided the electron transfers enough energy, the atom will either become ionised (lose electrons) or become excited (the electrons in the atom go up energy levels); higher energy electrons will cause ionisation, and lower energy electrons will cause excitation. Energy levels are essentially ‘rings’ around the nucleus of an atom which electrons can occupy, which determine the amount of energy those electrons have.
When the mercury atoms in the vapour become ionised, a mixture of ions and free electrons is created which is known as a plasma. The plasma allows higher currents to flow through the lamp by increasing the conductivity of the gas.
On the other hand, when the mercury atoms become excited, they are very unstable and quickly return to their ground state (the lowest energy level at which the electrons are most stable), releasing photons of ultraviolet radiation. These photons strike the phosphors (remember, I mentioned these earlier) in the coating and are absorbed. The energy is re-emitted as visible light, and some energy is transferred as heat. This effect of absorbing electromagnetic radiation and emitting it as light is known as fluorescence, hence the name fluorescent light.
Wowee, I feel so enlightened with all that fascinating knowledge about fluorescent lights! Please, oh please Mr Harvey, continue to deliver such entertaining and informative content. I will make sure to leave a comment if I have any questions and to share this amazing post with all of my friends and family.
Stay tuned and don’t panic,