How does an electric bulb light up

The Chronify

October 8, 2025

When electricity flows through a wire into a bulb, the wire inside the bulb becomes hot and starts to glow. This happens because of the filament inside the bulb. The filament is very thin and offers resistance to the flow of electric current. As a result, the electrical energy is converted into heat and light energy.

The filament is usually made of a metal called tungsten. Tungsten melts at very high temperatures.
To prevent the filament from burning out, all the oxygen inside the bulb is removed.
Instead, inert gases (which do not react chemically) are used to fill the bulb.
Some bulbs also contain halogen gases such as iodine and bromine.

LED Bulbs

LED stands for Light Emitting Diode. These bulbs produce light by passing electricity through a semiconductor material.
LED bulbs are more energy-efficient than traditional bulbs.
They are also long-lasting and durable.
LEDs require less power to produce light, because very little energy is wasted as heat.

Tungsten

Tungsten filaments are very thin and fragile.
If such a bulb is dropped on the floor, the outer glass may not break but the delicate filament inside can easily snap.

Halogen

Halogen gas helps protect the filament and extend the life of the bulb.
Halogen bulbs typically last twice as long as regular incandescent bulbs.