The filament of a torch bulb is made of tungsten. Tungsten is used because it has a high melting point, allowing it to glow brightly without melting when electricity passes through it. This makes it ideal for producing light in incandescent bulbs.

Introduction to Torch Bulb Filaments
Torch bulbs, commonly used in flashlights, contain a filament that plays a critical role in producing light. Understanding the material used for this filament helps us appreciate its functionality and efficiency.
Importance of the Filament Material
- The filament must be able to withstand high temperatures without melting.
- It should have a high electrical resistance to convert electric energy into light effectively.
Why Tungsten is Used
- High Melting Point: Tungsten has an incredibly high melting point of about 3,422 degrees Celsius. This allows it to operate at higher temperatures, producing more light without melting.
- Durability: Tungsten is also very durable, which means it can last longer compared to filaments made from other materials. This is particularly important for torch bulbs that need to withstand frequent use.
- Efficient Light Production: When electricity passes through tungsten, it heats up and emits a bright white light, making it ideal for illumination.
Why Other Materials are Not Suitable
- Aluminum: While lightweight, aluminum has a lower melting point, making it unsuitable for high-temperature applications like torch bulbs.
- Plastic: Plastic is an insulator and cannot conduct electricity, making it impractical for use as a filament.
- Copper: Although copper conducts electricity well, it also has a lower melting point than tungsten and would not be able to withstand the heat generated in a filament.
Conclusion
In summary, the filament in a torch bulb is made from tungsten because of its high melting point, durability, and efficiency in light production. These properties make tungsten the best choice for ensuring reliable and bright illumination in portable lighting devices.