Fourth-graders are currently learning about magnetism and electricity. We recently created some circuits using D-cells, wires, motors and light bulbs (components) and learned that the tiny wire inside a light bulb that makes it light up is called filament. It's made of a metal called tungsten. Tungsten is used because it stays solid at very high temperatures. Also, all the air in a light bulb has been sucked out to make it work. If air wasn't removed, the wire would burn up instantly. Electricity flows through the filament causing it to heat up. This heat makes the tungsten glow. As the filament heats up, it gives off light. The tungsten slowly vaporizes, or turns into a gas.When a light bulb “burns out,” it is because the filament has vaporized. The black film on the inside of a burned-out lightbulb is resolidified tungsten vapor (gas). Wow, huh?
