How does a light bulb work?

Traditional (Incandescent) light bulbs:

The electricity flows through the filament, a tiny wire inside the light bulb. This element has a strong resistance, which in turn causes friction when electricity flows through it, resulting in the filament of the light  bulb heating up and it starts to glow, converting electrical energy to light energy.

After numerous hours, the filament of the light bulb would burn out and the light bulb will not glow any longer.  Even though we refer to it as the light bulb ‘burning’ out, this is not correct. It actually evaporates over time when being switched on. You can notice this by the dark discolouring on the glass of the light bulb as time passes. Inside the glass, gasses like argon or nitrogen is used, because it is inert (electrically non-conducting) and cannot unite with the filament of the light bulb.

So why does it burn out, you might ask. A light bulb has no oxygen inside it and is filled with the above mentioned gasses. This does not prevent the atoms bouncing off the surface of the light bulb filament due to the intense heat in the bulb. Because of this, the filament wears thinner; eventually it becomes so worn out that is snaps apart. The two broken ends fall away from each other, breaking the resistance spark and the light bulb will not glow any longer. The inert gas does not allow the filament to burn, it just allows it to glow brightly, producing the light effect.

Fluorescent & Halogen light bulbs:

The incandescent light bulb uses just enough electric current to make the filament glow, without making it so hot that it melts. Other lights, not incandescent, like fluorescent tubes, contains argon gas and mercury vapour instead of a filament. When an electrical current moves through the gas ultraviolet, radiation is emitted.  The UV radiation collides with the phosphors coated on the inside of the light bulb, which creates light. A halogen light bulb is very similar to the incandescent light bulb, both have filaments. The difference is that halogen bulbs has a small amount of halogen (chlorine or fluorine), which increases the lifespan of the filament. This light bulb is used at a higher temperature, which is why it produces more of a blue light.

LED light bulbs:

LED (Light emitting diode) bulbs might be more expensive than incandescent bulbs, but they last up to 25 years longer. Unlike the traditional light bulbs, there is no filament in LEDs, so there is nothing to burn out. It is a simple electric circuit and does not use heat to produce light. Instead, it utilizes a small electrical current to excite electrons, which releases photons, which we perceive as light. This is also why the LED bulb is cooler than the regular bulbs. Thus, they are far more efficient at turning energy into light, than incandescent and CFL bulbs. LEDs can produce a spectrum of colours quite easily, while using very little electricity to create that light. As the light bulb gets older, it just gets dimmer, instead of burning out.  The biggest benefit of LEDs is its lifespan; they last 5 times longer than a CFL bulb. During that time, this light bulb uses 300 kilowatt hours of electricity. This means that an LED bulb saves 400 kilowatt hours of electricity compared to the CFL and compared to the 2700 kilowatt used by an incandescent bulb.  This light bulb is for sure the best bet energy & cost wise.




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