What is a tungsten filament? (with photos)

Lamps with tungsten filament.

A tungsten filament is a thin filament of metal that glows brightly when an electric current passes through it. When rolled up and sealed inside a glass container filled with an inert gas, a tungsten filament can glow brightly enough to light up a room. It was the inclusion of a tungsten filament in their electric lighting system that resulted in the world giving Thomas Edison credit for inventing the electric light bulb, when in fact dozens of scientists were experimenting with electric light.

Inventor Thomas Edison used tungsten filament to create his light bulb.

Tungsten is an element (symbol: W; atomic number 74) discovered in the late 18th century. Almost twice as dense as lead, it has the highest melting point of all metals at 6192°F (3422°C); of all the elements, only the melting point of carbon is higher. These properties make tungsten very useful not only in electrical technology but also for military applications such as hardening weapons. Another use of tungsten is as a component of jewelry, where it is combined with other materials to form very hard, shiny compounds, although they can be brittle.

Tungsten is often used to make jewelry.

When Thomas Edison and other scientists were working on developing the electric light bulb, they experimented with various materials for the light-producing filament. Until the beginning of the 20th century, the most successful incandescent light bulbs used a carbonized bamboo filament, which lasted about 1,200 hours. Edison was not the first to use tungsten, which was introduced as an incandescent light bulb filament in Europe in 1904.

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In 1906, Edison’s General Electric (GE) company developed a process to make pure tungsten flexible enough to form a coiled wire. Using a coiled wire allowed GE to increase the surface area of ​​tungsten that would go inside the bulb. In 1911, the company already manufactured and sold light bulbs with the new filaments, which lasted longer than all others. Advances in this technology have continued almost uninterrupted, so that the cost of operating an incandescent light bulb at the turn of the 21st century was less than 5% of what it was in 1911.

Despite its success as a light source for incandescent lamps, tungsten filament is remarkably inefficient at producing light. About 90% of the energy used to operate an incandescent light bulb is emitted as heat, not light. As more efficient methods of producing light were developed, notably fluorescent lighting and light-emitting diodes (LEDs), some called for a ban on incandescent light bulbs as an energy conservation measure.

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