Operation of incandescent lamps

A light bulb works based on the principle of electrical resistance and heat. Here's a simple explanation of how a light bulb functions:

1. Power Supply: When you turn on a light bulb, an electric current flows through it. The current enters the bulb through the metal contact point at the bottom.

2. Filament: Inside the light bulb, there is a thin wire made of tungsten, called the filament. Tungsten is used because it has a very high melting point, meaning it can get extremely hot without melting.

3. Resistance and Heat: As the electric current passes through the filament, it encounters resistance. Due to this resistance, the filament heats up, usually to about 2500 degrees Celsius.

4. Light Emission: Because of the heat, the filament begins to glow and emit light. This happens through thermal radiation: when a material gets hot enough, it emits light. In a light bulb, this is visible light.

5. Glass Enclosure: The filament is surrounded by a glass enclosure. This enclosure is often filled with an inert gas, like argon, to prevent the filament from burning up through contact with oxygen in the air. The glass also protects the filament from physical damage.

6. Energy Loss: The main drawback of a light bulb is that much of the energy it consumes is converted into heat rather than light. This makes light bulbs less efficient compared to other modern light sources, like LED bulbs.

In summary, a light bulb works by sending an electric current through a thin tungsten wire, causing it to heat up and emit light.