How does a fiddly little piece of wire encased in a glass bubble manage to illuminate so well? James May on how the humble lightbulb does its job, more by accident than design.

The lightbulb has been shedding light in our homes and workplaces since the 1870s. and it’s been doing a sterling job considering the light it creates is a by-product of the chemical processes going on.

Essentially, the lightbulb is a very thin filament of hard-to-melt metal – tungsten, usually – encased in a glass bulb filled with inert gases so that the filament doesn’t oxidise and disintegrate. The electricity causes the wire to glow and a portion of that energy is turned into light.

But, it turns out, the lightbulb might have been more accurately called the ‘heatbulb’ – most of its energy gets turned into heat. Which is why the bulbs are being slowly phased out in favour of alternatives like LED lights.

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