Which mineral is commonly used in filaments of traditional incandescent lightbulbs?

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

Answer: (A)

Keeping a filament intact while it gets incredibly hot is the key idea. Incandescent bulbs work by heating a thin filament until it glows, so the material must withstand very high temperatures without melting or evaporating. Tungsten is ideal because it has an extremely high melting point, about 3,422°C, and very low vapor pressure at those temperatures, which means it doesn’t evaporate away quickly. It’s also strong enough to be drawn into the ultra-thin wires used as filaments. Other metals like nickel, copper, and aluminum either melt or vaporize at these temperatures or don’t hold up well under the heat, so they aren’t suitable for long-lasting filaments.