The story of Edison’s invention of the electric light

Before the advent of the electric light, the most commonly used lighting tools were kerosene lamps or gas lamps. This kind of lamp burns kerosene or gas, so it produces strong black smoke and a pungent odor. It is also very inconvenient to add fuel and clean the lampshade frequently. What's more serious is that this kind of lamp can easily cause fire and cause catastrophe. Over the years, many scientists have tried their best to invent an electric light that is both safe and convenient.

In the early 19th century, a British chemist used 2,000 batteries and two carbon rods to make the world's first arc lamp. But this kind of light is too strong and can only be installed on streets or squares, and cannot be used by ordinary families. Countless scientists have racked their brains to create a cheap, high-quality, durable household electric light.

The day has finally arrived. On October 21, 1879, an American inventor finally ignited the world's first practical electric lamp through long and repeated experiments. Since then, the name of this inventor, like the electric light he invented, has entered thousands of households. He was Edison, who was praised as the "King of Invention" by later generations.

On February 11, 1847, Edison was born in Milan, Ohio, USA. He only studied in school for three months in his life, but he was studious and diligent in thinking. He invented more than 1,000 achievements such as electric lights, phonographs, and movie cameras, and made significant contributions to mankind.

When Edison was 12 years old, he was obsessed with scientific experiments. After his tireless self-study and experiments, when he was 16 years old, he invented an automatic telegraph that sent a signal every hour. Later, automatic ticket counting machines, the first practical typewriter, double and quadruple telegraph machines, automatic telephones and phonographs were invented one after another. With these inventions, Edison was not satisfied. In September 1878, Edison decided to launch an attack on the fortress of electric lighting. He read a lot of books about electric lighting and was determined to make electric lights that were cheap, durable, safe and convenient.

He started with incandescent lamps. A small piece of heat-resistant material is placed in a glass bubble. When the current burns it to a white-hot level, it emits light due to heat. He first thought of charcoal, so he put a small piece of charcoal wire into a glass bubble, but it broke immediately as soon as he was powered on.

"What's the reason for this?" Edison picked up the carbon wire broken into two pieces and looked at the glass bubble. After a long time, he suddenly remembered, "Oh, maybe it's because there is air in it. The oxygen in the air helped the charcoal filament burn, causing it to break immediately!" So he used his handmade air extractor to remove as much air as possible from the glass bubble. As soon as the power was turned on, it did not turn off immediately. But after 8 minutes, the light still went out.

In any case, Edison finally discovered that the incandescent lamp is very important in the vacuum state. The key is the carbon filament. This is the crux of the problem.

So what kind of heat-resistant material should be chosen?

Edison thought about it and decided that platinum has the highest melting point and strong heat resistance! So Edison and his assistants tried several times with platinum. However, although this kind of platinum with a higher melting point extended the lighting time of the electric lamp a lot, it still had to automatically turn off and light up again from time to time, which was still not ideal.

Edison was not discouraged and continued his experimental work. He successively tried various rare metals such as barium, titanium, and indium, but the results were not satisfactory.

After some time, Edison made a summary of the previous experimental work and wrote down all the various heat-resistant materials he could think of. There were as many as 1,600 kinds in total.

Next, he and his assistants classified the 1,600 heat-resistant materials and began testing them. They tried many times, but platinum was still the most suitable. Thanks to improved extraction methods that create a higher degree of vacuum inside the glass bulb, the lamp life has been extended to 2 hours.

But this kind of lamp made of platinum is too expensive. Who is willing to spend so much money to buy a lamp that can only be used for 2 hours?

The experimental work fell into a trough, and Edison was very distressed. One cold winter, Edison sat by the fire, looking at the blazing charcoal fire, and couldn't help but murmur to himself: "Charcoal..."

I have tried charcoal strips, what should I do? Edison felt hot all over and pulled off the scarf around his neck. Seeing the scarf made of cotton yarn, Edison suddenly had an idea in his mind:

Yes! The fiber of cotton yarn is better than that of wood. Can this material be used?

He hurriedly pulled off a piece of cotton yarn from the scarf and roasted it on the fire for a long time. The cotton yarn turned into charred charcoal. He carefully put the carbon filament into the glass bubble and tested it. The effect was indeed very good.

Edison was very happy, and then he made a lot of carbon filaments made of cotton yarn and conducted many experiments in succession. The life of the light bulb was suddenly extended by 13 hours, and later reached 45 hours.

As soon as the news spread, it shocked the whole world. The price of gas stocks in London, England plummeted, and the gas industry was also in chaos. People had a premonition that lighting gas lamps would soon become a thing of the past, and the future would be the age of electric light.

Everyone congratulated Edison, but the cute Edison didn’t look happy at all. He shook his head and said, "No, we have to find other materials!"

"Why, it stayed on for 45 hours. Not yet?" the assistant asked in surprise. "No! I hope it can last for 1,000 hours, preferably 16,000 hours!" Edison replied.

As we all know, it is good to keep the light on for more than 1,000 hours, but what kind of materials are suitable?

Edison already knew what was going on. Based on the properties of cotton yarn, he decided to look for new materials from plant fibers.

So, the marathon experiment began again. Edison experimented with all plant materials he could find. He even used horse mane, human hair and beards as filament experiments. Finally, Edison chose bamboo. Before the experiment, he took out a piece of bamboo, looked at it through a microscope, and jumped with joy. So, the carbonized bamboo filaments were put into the glass bulbs, and after being powered on, the bamboo filament bulbs lit up continuously for 1,200 hours!

At this time, Edison finally breathed a sigh of relief. His assistants congratulated him one after another, but he said seriously: "There are many bamboos around the world, and their structures are different. We should choose carefully!"

The assistants were deeply moved by Edison’s scientific attitude of striving for excellence, and they volunteered to inspect various places. After comparison, a kind of bamboo produced in Japan was most suitable, so a large amount of this bamboo was imported from Japan. At the same time, Edison opened a power plant and set up wires. Soon after, the American people began to use this cheap, high-quality, durable bamboo filament light bulb.

The bamboo filament lamp has been used for many years. It was not until 1906 that Edison switched to using tungsten filament, which improved the quality of light bulbs and continues to be used today.

When people light up the electric light, they always think of this great inventor, who brought endless light to the darkness. In 1979, the United States spent millions of dollars on a year-long commemorative event to commemorate the 100th anniversary of Edison's invention of the electric light.