glasbulb

A glasbulb, or glass bulb, is a sealed glass enclosure used in electrical lamps and various instruments. The envelope is typically made from soda-lime glass, but high-temperature variants may use borosilicate glass or fused quartz. The bulb can be evacuated to create a vacuum or filled with an inert gas such as argon or nitrogen, sometimes with a small amount of halogen for halogen lamps. The sealed environment protects internal components from oxidation, moisture, and contamination while also providing mechanical support.

In lighting applications, the glass bulb encloses a filament or other light-emitting element. In incandescent lamps, a tungsten filament sits inside a vacuum or gas-filled bulb to reduce filament degradation. Halogen lamps use a quartz or fused silica envelope with a halogen cycle to extend lamp life and efficiency. Bulbs come in a variety of shapes and sizes, including spherical, globe, candle-like, and tubular designs, and with different base configurations such as screw bases (for example E26/E27) or bayonet and pin bases.

Glass bulbs are also used in non-lighting contexts, such as thermometers and vacuum tubes. In thermometers, the glass bulb serves as the liquid reservoir, and its volume influences response time and accuracy. In older electronics, glass envelopes form vacuum tubes that house electrodes and enable electron flow.

Manufacture and disposal: glass bulbs are formed by blowing or drawing from glass tubing and then sealing around a base or fitting. They are fragile and recyclable, but many contain hazardous substances (such as mercury in some devices) and should be processed according to local environmental regulations.