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How do fluorescent lamps glow?

Fluorescent lamps light up our homes and classrooms. Fluorescent lamps come in different shapes and sizes. But when you turn on the switch, they all start to glow white after a few seconds. What makes them glow like that?

The middle of a fluorescent lamp is like a tube. When you turn on the switch, electricity travels through the space in the tube. The electrons collide with the mercury vapor inside the tube, which creates light. But people can’t see the light made by these collisions. This first light shines against the fluorescent material coated on the inside of the tube. The fluorescent material changes the light into light that we can see. This process is why it takes a few seconds for a fluorescent lamp to start to glow.