Glödtråden

Glödtråden, commonly known as the incandescent filament, is a key component in traditional incandescent light bulbs. It consists of a thin wire, typically made from tungsten, which is coiled to increase its surface area and efficiency. When an electric current passes through the filament, it heats up to a high temperature, causing it to glow and emit light. This process is known as incandescence, where the filament radiates visible light along with infrared radiation (heat).

Tungsten is used due to its high melting point (3,422 °C or 6,192 °F), which allows it to operate at high temperatures without vaporizing quickly. The filament is sealed inside a glass bulb filled with an inert gas, such as argon or nitrogen, to slow down the evaporation of the tungsten. Without this gas, the filament would burn out much faster due to oxidation.

Glödtråden was first developed in the late 19th century as part of efforts to create practical electric lighting. Early versions used materials like carbon, but tungsten became the standard in the early 20th century due to its superior durability and efficiency. While incandescent bulbs with glödtråden were widely used for over a century, they have largely been phased out in favor of more energy-efficient alternatives, such as LED and fluorescent lights, due to their lower energy consumption and longer lifespan.

Despite their inefficiency—only about 10% of the energy is converted into light, with the rest lost as heat—glödtråden remains a fundamental concept in lighting technology, illustrating the principles of thermal radiation and electrical resistance. Modern variations of incandescent bulbs, such as halogen bulbs, use similar filament technology but with improved materials and designs to enhance performance.