Topic: Compact Fluorescent Lamp

How compact fluorescent lamp (CFL) is more energy efficient? What is the void inside the tube filled in?


Re: Compact Fluorescent Lamp

Compact fluorescent lamps (CFL) operate on different principle than incandescent lamps. In incandescent lamp, the filament is heated to make it glow. Here, although part of heat energy is converted to light energy, there is substantial wastage (pobably 90%) of energy as heat itself. As there is no such extreme heating involved in functioning of  CFL, energy losses through heat are minimal. This is one of the reasons for lower energy requirements for CFL.

Second reason for CFL to be more energy-efficient is that our eyes are more sensitive to the light spectrum produced by CFL than that produced by incandescent lamps. Hence, CFL requires less energy for generating same illumination vis-à-vis incandescent lamp.

In CFL, the void is filled with mercury vapour. Mercury atoms get excited when are struck by electrons produced by electrode. The excited mercury atoms emit ultra-violet photons which hit the walls of CFL. The walls of CFL are coated with a material called phosphor. (Phosphor is a mixture of inorganic compounds of strontium, magnesium, barium, lanthanum, yttrium, etc.) Phosphor when struck with ultra-violet photons, in turn, produces visible photons i.e. visible light.

Last edited by rajeev (04-10-2010 <> 08:25:29 AM)


Re: Compact Fluorescent Lamp

I heard that mercury vapours are poisonous. Then, it must be dangerous to use Compact fluorescent lamps.

I am confused...


Re: Compact Fluorescent Lamp

What you say is true. Each CFL contains about 5 mg of mercury. If  CFL breaks,  there is a dimmed risk of mercury poisoning. Hence, some care has to be taken during the cleaning operation in case of such eventuality. The windows are to be kept open for about 15 minutes. The mops used for cleaning should be properly packed and sent to disposal site. Vacuum cleaner should not be used for cleaning operations, as it may enhance the mercury spillage at a later stage.

Amount of mercury used in CFL is very small. Even conventional thermometer which we use for measuring the body temperature contains more mercury than this. According to experts, if a CFL shatters on the floor, the greatest danger may be the broken glass (rather than mercury). Nevertheless, attempts are on to manufature recyclable CFL lamps. These CFL lamps will be usable even after their operative period is over.

In fact, coal burning employed for power production, itself releases substantial quantities of mercury into atmosphere. Use of CFL is going to reduce overall power requirements thereby reducing the coal burning. This will obviously lead to reduced release of mercury.

Last edited by rajeev (10-10-2010 <> 22:29:56 PM)


Re: Compact Fluorescent Lamp


Now I am convinced about the merits of Compact Fluorescent Lamps....


Re: Compact Fluorescent Lamp

The explanation about energy saving by CFL is quiit fruitful to the people.
   I liked it too much !
    Prof. B B Inamdar


Re: Compact Fluorescent Lamp