On what principle does the bulb work?

The bulb works on the principle of incandescent

It has a thin filament (wire) through which when the current flows, it heats up and starts giving light.

The emission of light due to heating is called incandescence.

Structure of Bulb

Incandescent lamp

Incandescent lamp or incandescent lamp is colloquially called bulb. It generates light by incandescence. The emission of light due to heating is called incandescence. It has a thin filament (wire) through which when the current flows, it heats up and starts giving light. The filament is kept inside the glass bulb so that the atmospheric oxygen cannot reach the very hot filament and thus cannot weaken the filament by acting.

Features

Incandescent lamps are made of various sizes, voltages and power. Bulbs ranging from 1.5 V (torch bulb) to 300 V are readily available. Similarly, bulbs ranging from 1 watt to thousands of watts are made. Incandescent bulbs have the characteristic that their manufacturing costs are very low.

Multi Colour Bulb

These are operated by connecting them directly to the appropriate voltage without any additional frills; They work on both AC and DC. For these reasons, this lamp is often used in homes. But its optical efficiency is low i.e. it takes relatively more electricity to produce the same light. For this reason, other light sources (such as CFLs) are gradually gaining popularity and their use is decreasing.