What material is used for the filament in incandescent lightbulbs?

What material is used for the filament in incandescent lightbulbs?

• A. Tungsten
• B. Copper
• C. Aluminum
• D. Nickel

Answer: (A)

Filaments in incandescent bulbs must stay solid and intact at extremely high temperatures long enough to glow visibly. Tungsten is used because it has the highest melting point of any metal and a very low vapor pressure when hot, so it won’t melt away or evaporate quickly as it reaches the necessary temperatures. It also can be drawn into very thin, strong wires, which lets a long, slender filament glow reliably. Other metals like copper, aluminum, or nickel would melt, creep, or evaporate much sooner under those conditions, so they’re not suitable for incandescent filaments.

Filaments in incandescent bulbs must stay solid and intact at extremely high temperatures long enough to glow visibly. Tungsten is used because it has the highest melting point of any metal and a very low vapor pressure when hot, so it won’t melt away or evaporate quickly as it reaches the necessary temperatures. It also can be drawn into very thin, strong wires, which lets a long, slender filament glow reliably. Other metals like copper, aluminum, or nickel would melt, creep, or evaporate much sooner under those conditions, so they’re not suitable for incandescent filaments.