How do Light Bulbs Work

We sheds some light on one of the most world-changing inventions.

Today the electric light bulb is an essential part of society, with virtually all streets, homes and vehicles installed with one. The invention has literally lit up the Earth and transformed how we live.

The beginning of the journey to the electric light bulb began in 1799 when Italian physicist Alessandro Volta invented the voltaic pile (battery). The details of the battery soon spread through Europe, with many scientists replicating it and experimenting with its power-giving capabilities. One of the most notable of these scientists was British physicist Sir Humphry Davy who built one at the Royal Institution in 1802. In 1810, after much experimentation, Davy invented the first arc lamp, a temporary electric light source enabled by connecting two carbon rods to the battery’s terminals and bringing them to within a couple of millimetres of each other. This caused the electric current to jump between the two, creating a bright plasma stream that illuminated the immediate surrounding area.

Unfortunately, the intensity of the plasma soon caused the carbon rods to burn away and the invention did not gain commercial traction. However, the use of carbon and a variety of other metals as electrodes and filaments did, leading a number of scientists to create crude lights. None were sustainable, however.

The next major breakthrough came in the realization that the electrodes/filaments used in incandescent lights could be protected from quick destruction by placing them within a vacuum filled with an inert gas (as demonstrated by Warren de la Rue in 1840). This, along with the later discovery that filaments could be carbonized, allowed basic light bulbs to be created that, rather than lasting seconds or minutes, would work for hours and eventually days. Indeed, throughout the mid-i9th century numerous scientists, and even an illusionist, showed such bulbs to their friends and at public demonstrations.

This series of prototypes culminated in 1879 when Joseph Swan successfully demonstrated and then sold a light that used a single coil of carbonized artificial cellulose fibre embedded within an airless glass bulb. This was the first commercially sold incandescent light bulb. Critically though, its adoption was only on a very small scale as, despite the bulb proving resilient, the power source needed was largely unavailable, with no electric infrastructure in place to support a wide-scale rollout.

This set the scene for Thomas Edison, who in 1880 successfully patented his own light bulb, which aside from being an improved design to that of Swan, was backed up by Edison’s own electric generator, a package that would enable him to largely corner the new market for electric lighting that was set to take off.

Bright sparks: the race to the commercial light bulb

Sir Humphry Davy – In 1802 British scientist Sir Humphry Davy used his large battery to pass a current through a thin strip of platinum. The experiment worked, but the platinum did not glow very brightly and wore out too quickly to be practically implemented into a lamp.

Warren de la Rue – In 1840 chemist and astronomer Warren de la Rue enclosed a platinum coil in a vacuum tube and passed an electric current through it. This was one of the first true light bulbs as we know them today, however its cost and complexity made it impractical to roll out.

Jean Robert-Houdin – This illusionist created his own incandescent light bulbs and showed them publicly at his estate in 1852. Again, they were curiosities and no practical production process or cost-efficient materials meant they couldn’t be produced commercially.

Alexander Lodygin – In 1872 Russian Lodygin obtained a patent for an incandescent light bulb that used carbon rods in a nitrogen-filled, sealed bell glass receiver. He later moved to the US and applied for many patents, showing a molybdenum filament at the Paris World Fair in 1900.

Joseph Swan – This British physicist arguably created one of the first sustainable light bulbs, demonstrating his carbon rod bulbs in 1878-9. He received a patent and began installing them in a few homes and theatres. He later partnered with Edison and set up the Ediswan Electric Company.

Facts about the light bulb

Evaporation – Under sustained use the filament of modern-day tungsten bulbs will evaporate before condensing on the inner surface of the glass envelope, blackening it.

Halogen – Halogen lamps reduce evaporation of their filament and the darkening of the surrounding glass by filling the lamp with halogen gas at a very low pressure.

Inefficient – Despite modern bulbs lasting for lengthy periods, about 90 per cent of the power they consume is emitted as heat, rather than light.

Bulb boom – In 1885 there were estimated to be about 300,000 incandescent lights in use, a number which then exploded over the subsequent decades up to 795 million by 1945.

Old-timer – The Livermore Centennial Light Bulb at a fire station in California, USA, has been burning non-stop since 1901. It is the record holder for longest operational bulb in the world.