Why is tungsten used in light bulb filaments?

Tungsten is used in light bulb filaments because it has a high melting point and good electrical conductivity.

Tungsten, a metal element with the symbol W, is chosen for light bulb filaments primarily due to its high melting point. This property allows it to withstand the high temperatures generated when electric current passes through the filament, causing it to glow and produce light. Tungsten's melting point is around 3422 degrees Celsius, which is one of the highest among all metals. This means that it can endure the heat produced in the bulb without melting, thus prolonging the lifespan of the bulb.

In addition to its high melting point, tungsten also has good electrical conductivity. This is a crucial property for a light bulb filament, as it needs to conduct electricity efficiently to produce light. When an electric current is passed through the tungsten filament, the electrons in the metal atoms get excited and move to higher energy levels. When they return to their original energy levels, they release energy in the form of light and heat. This process is known as incandescence.

Furthermore, tungsten is a ductile metal, meaning it can be drawn into very thin wires without breaking. This is another important characteristic for a light bulb filament, as it needs to be thin to increase its resistance to the flow of electricity, thereby producing more light.

Lastly, tungsten is relatively abundant and easy to extract from its ores, making it a cost-effective choice for light bulb production. Despite the advent of more energy-efficient lighting technologies, such as LED and CFL, tungsten filaments are still widely used in certain types of light bulbs due to these advantageous properties.