If light fixtures are powered through electricity, why do light bulbs need to be replaced?
In: Engineering
There is more to this question than just the actual physical reason for it. Light bulbs are probably the most prominent example of ‘planned obsolescence’, which means that they are designed to only last for a given amount of time. The reason for this, was that in the early days of the light bulb, companies were able to make light bulbs that could technically last for centuries. Some of those bulbs still exist and have been burning continuously for more than a century! However, if all light bulbs lasted that long, after the market had been saturated, nobody would ever need to buy new lamps. Thus, the companies who made lamps decided to jointly sign an agreement that they would all make their lightbulbs less resilient, so that they would eventually break after around 1000 hours. This pact is known as the ‘Phoebus cartel’, and included manufacturers like Philips, Osram and General Electric.
However, this was the case for incandescent light bulbs. Other types of light bulbs may have different light spans. In general, the ‘burning out’ has to do with the wear on the internal parts that eventually break the circuitry in the lamp. The wires can corrode, they expand and shrink constantly because of the heat, and over time, these factors make it so that the parts become more and more ‘brittle’, and eventually, usually when turning a lamp on, they fail or break.
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