Actually, you can’t see the light that is immediately given off in the long, narrow tubes of a fluorescent lamp as you can in an electric light bulb, where the glowing tungsten wire lights up the surrounding area. For in a fluorescent lamp, the light comes from a special gas called mercury vapor. When electricity flows through this mercury vapor inside a glass tube, the light it produces is invisible to the human eye.
How then do fluorescent fixtures manage to light up a room? The answer lies in a chemical powder called phosphor, which is sprayed against the inner surface of the glass tube. When electricity goes through the mercury vapor, the invisible light hits the particles of phosphor powder and makes them glow. This glowing light is known as fluorescence.
When you turn on a fluorescent light, the starter inside the unit lets in the electric current coming from a power station’s generator. The electric flow reaches an electrode, a coil of fine wire, at each end of the glass tube. The electricity is pushed off the electrode into the space inside the glass tube. Here, it hits the mercury vapor and then the phosphors, which react by glowing.
It takes particles of blue, green, and yellow phosphor powder to produce a fluorescent’s white light!