What Is Inside A Fluorescent Lamp?


Sometimes we are so familiar with a piece of common equipment or a simple machine that we hardly know or bother about its working. Take the case of a door bell working principle or of a simple tube light which is found in every home and is also known by the name of a fluorescent lamp. I am sure there would be hardly a soul who hasn’t heard about or used a tube light. But do you really understand the working concept of a tube light or have you ever thought what is inside a fluorescent lamp which makes it glow? If not, then you are just at the right place and we will study this in detail in the subsequent sections

Background information

Before you are in a position to understand what lies behind the tubular structure which emits white milky light, there are certain basic concepts of physics which you certainly need to know. Otherwise you may not be able to fully appreciate what I am saying. Of course we are not going to have a deep physics tutorial here but only a broad overview.

I am sure you have heard that light is a form of energy and as per quantum physics it can be broken down into finite chunks known as photons and it travels in this form. So where do these photons originate from? Well they are released when electrons jump from a higher energy level to a lower energy level. You can read about energy levels and bands in other articles in this channel.

So if there is a way in which electrons can be made to traverse across these energy levels as required, they would continuously keeping jumping up and down and keep releasing photons. This is exactly what happens not only in fluorescent lamps but even the ordinary light bulbs. Only the difference lies in the method of making these electrons jump across the energy barriers.

What is inside a fluorescent lamp?

Coming back to this simple million dollar question; to state in the most simple terms a fluorescent tube or the ordinary tube light is a cylindrical glass enclosure which has a certain arrangement whereby the electrons of the material inside the tube are artificially excited and made to release light photons in the visible spectrum. The various components that are present inside are as follows.

  • Inert Gas – this is normally Argon gas which is used to provide an inert atmosphere inside the tubular enclosure
  • Electrodes – they are used to supply the electrons which ionize the inert gas
  • Mercury – this is used to emit UV light
  • Phosphor – this absorbs the UV energy created inside the tube and deliver visible light energy which is used to light up the surrounding of the tube light
  • Starter – it is used in old tubelights to provide path of lower resistance till the tube light starts
  • Choke/Ballast – this is used to provide adequate voltage for the operation of the fluorescent lamp

Please note one important point that though I have written that these components are inside the fluorescent lamp, not all of the above are physically located inside the glass tube of the tubelight but many of them such as the choke, starter and the relevant wirings are outside of the glass tube enclosure. At the same time they do form an important part of the overall starting arrangement and the tube cannot work without these components.

Better light and sight

One of the biggest advantage of using a fluorescent lamp as compared to the normal filament bulb is that it produces white light which is pleasant as well as good illumination whereas the bulb produces yellowish coloured light and uses more electricity. A typical tubelight is several times more energy efficient than the normal light bulb.

We will study the actual working of these components in our next article