Why are tungsten filaments used in incandescent bulbs?

Tungsten filaments are used in incandescent bulbs due to their high melting point and resistance to heat.

Tungsten, a metal with the highest melting point of all the elements, is the material of choice for the filament in incandescent light bulbs. This is because the filament in an incandescent bulb must be heated to a very high temperature to emit light, and tungsten can withstand these temperatures without melting.

The filament in an incandescent bulb works by passing an electric current through it, which causes the filament to heat up and glow, producing light. This process is known as incandescence. The filament must be able to withstand the heat generated by the electric current without melting, which is why a material with a high melting point like tungsten is used.

In addition to its high melting point, tungsten also has a high resistance to electricity. This means that it takes a lot of energy to pass an electric current through it, which results in more heat being generated. This heat is what causes the filament to glow and produce light.

Furthermore, tungsten is a good conductor of heat, which means it can efficiently transfer the heat generated by the electric current throughout the filament. This ensures that the filament glows evenly, producing a steady light.

Tungsten also has a low rate of thermal expansion, which means it doesn't expand much when it's heated. This is important because if the filament expanded too much when it was heated, it could break or become deformed, which would cause the bulb to fail.

Finally, tungsten is a relatively abundant and inexpensive material, which makes it a cost-effective choice for use in incandescent bulbs. Despite the advent of more energy-efficient lighting technologies, such as compact fluorescent lamps (CFLs) and light-emitting diodes (LEDs), tungsten filaments are still widely used in incandescent bulbs due to these properties.