On this day, January 27, in 1880, Thomas Edison patented the electric incandescent lamp.
The incandescent light bulb was invented by Thomas Alva Edison in the year 1879. Despite the fact that it was invented over one hundred years ago, the principle behind the design is still the same today as it was then.
The incandescent light bulb is a glass bulb with a metal wire inside. When the power is on the light, of course, turns on. But what probably isn’t as obvious is the fact that the electricity that turns the light on isn’t directly producing the light. Instead, when power runs through the thin wire it encounters resistance. In overcoming this resistance heat is produced. In fact so much heat is produced that the filament glows white hot — the light that you can see.
To be practical the typical light bulb has to be able to last at least a few days. Therefore, a good filament must be chosen. The first practical light invented by Edison used a carbonized cotton thread filament which lasted about thirteen hours and thirty minutes. After more experimenting, Edison found that carbonized bamboo was a better choice. Even though bamboo still lasted a very short amount of time by today’s standards, people back then were quite content with it. In about 1904 the robust tungsten filament incorporated in today’s bulbs was introduced.
The material of the filament is not the only factor that affects the bulb’s life. The surrounding space is important too. Edison discovered that to make a light bulb filament last longer it has to be in a vacuum, otherwise the filament will burn out quickly as the air oxidizes the filament at high temperature. Hence, the glass bulb’s function is not solely for the protection of the materials inside and the user outside, but also to hold the required vacuum. Today certain gases, such as krypton or argon, are sometimes used to extend the life of the filament by preventing it from vaporizing quickly from its own heat.
The incandescent light bulb originally invented by Edison, hasn’t changed much over the years and remains a very practical way to produce light. However, as the more efficient (using less power to produce the same amount of light) fluorescent bulbs begin to replace it, it is quite possible that the incandescent light bulb will become a thing of the past.
Further Investigation
First Public Demonstration of Edison’s Light Bulb
Simple telling of the event.
The Great Internet Light Bulb Book
Everything you wanted to know…and then some.
Activities
Make a Light Bulb
Ready to try it yourself?
Books
Stories of Great Inventors by Hattie E. Macomber
This public domain download is written for early readers and covers Edison, along with Fulton, Whitney, Morse and Peter Cooper, who built the first locomotive in America.
Inventors by Philip G. Hubert
Very nice bio of Edison including a description of the incandescent light bulb. Also includes Franklin, Whitney, Morse, Goodyear, Fulton, Bell and others. In the public domain.
Notebooking Helps
My Science Experiment Notebook
17-page science experiment notebooking pages of all varieties. Includes scientific method.
Inventor – Edison
Edison notebooking pages to wrap up from Homeschool Share.
Our own unit studies, book studies and investigations that encourage research and independent learning.
