How do light bulbs work?

Author: Lena Fedda

Editors: Galiba Anjum and Liane Xu

Artist: Nicole Tseng

Before the arrival of electrical lighting, all sorts of techniques were used to provide light. From fire to candles to oil lamps, the list goes on! However, because of their high maintenance, none of these tools were efficient enough for human use, which led scientists to think of a better alternative that would potentially save both time and energy while generating higher-quality lighting.

Since the early 1800s, attempts have been made to create an electrical source of lightning. Contrary to popular belief, Thomas Edison wasn’t the first scientist to come up with the idea of light bulbs. Instead, he gathered a team of engineers, and together they worked on improving an existing idea. In order to understand the work that Edison’s team made, it is important to learn about the components of a light bulb and their functions first.

An ordinary light bulb consists of five major parts:

- The globe: The outer glass shell of the light bulb. This glass ensures maximum

light efficiency and provides strong support for the other parts of the bulb.

- Filament: The filament inside the light bulb is shaped as a coil to allow the

required length of the tungsten within its small environment to produce an

abundant amount of light.

- Wires and a stem: Within the inner center of the light bulb there is a centralized

stem made from glass, which supports the filament in its place. The connecting

wires ensure the steady flow of electricity through the components of the light bulb.

There is a wire that takes the electricity from the base of the light bulb and another

wire that completes the electrical circuit back to the base.

- Gases: Deep within the light bulb are inert gases, usually formed of argon and/or

nitrogen. These low-pressure gases prevent the filament inside the bulb from

burning out. They also relieve some of the stress on the glass globe from normal

atmospheric pressure, lessening the chance of glass breakage.

- The base: The base of the light bulb has three main functions. First, it securely

supports the light bulb within an electrical source unit, like a lamp or a light fixture.

The second job of the base is to transfer the electricity from the main electrical

source to the inside of the light bulb itself. The last function is to secure the globe

and all of the components inside the bulb, creating a reliable and convenient light

source.

To produce light, the concept of thermal radiation is used. By making an electric current go through the light bulb’s filament, the electrons of the latter lose a great portion of their kinetic energy due to the tungsten’s high resistivity. Therefore, this energy is absorbed by the filament’s atoms, exiting their electrons and making them jump to greater energy levels temporarily until they go back to their initial level emitting photons (basic unit of light).

Light bulbs give off different colors of lighting due to differences in the wavelength of photons. This can be attributed to the differences in the amount of absorbed energy which depends on the electrons’ positions which leads us to conclude that different sorts of atoms will create different sorts of light photons.

It is no surprise that the electric light bulb has been called the most important invention since man-made fire. It allows mankind to extend its hours, maximize productivity levels and the possibility of making money in restaurants and entertainment, and stores into the evening for enhanced profit and productivity.

Citations:

How Light Bulbs Work. (n.d.). Retrieved September 12, 2020, from https://www.real-world-

physics-problems.com/how-light-bulbs-work.html

Loa, J. (2013, September 13). How an Incandescent Light Bulb Works. Retrieved September

12, 2020, from https://blog.1000bulbs.com/home/flip-the-switch-how-an-incandescent-

light-bulb-works

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