Electric Light Bulbs

The electric lights that you use every day are a fairly recent invention. Thomas Edison invented the first practical light bulb only about 125 years ago.

Edison did hundreds of experiments before he found the right material for the filament. The filament is the tiny wire inside the bulb. When electricity flows through the filament, the wire gets hot and gives off light. Materials with low resistance to an electrical current do not get hot enough to give off light. Materials with too much resistance get too hot and burn up.

Early light bulbs used carbon filaments, which burned out after about 13 hours. Later, a metal called tungsten was found to work better than carbon. Light bulbs with tungsten filaments burn much longer than those with carbon filaments.