why did Edison use toungston in vacuum to make a bulb?

Question

Thomas Alwa Edison who invented electrical bulb,used the metal toungston to conduct current in vacuum so that it emitted light.why did he use it in vacuum?

Answer 1

Edison's idea was to make a thin metal wire glow by passing current through it. This worked but the wire , now called a filament, would break after a short time and the light would go out.
He discovered that Tungsten or Wolfram, was stronger and lasted longer, then realize that the high heat was causing oxidation (rust) which eroded and weakened the filament. Oxidation can only happen with air present, so he removed it by using a vacuum.

Answer 2

Actually the original Edison lamps had a carbon filament. In the text below understand the nitrogen is very low pressure gas. It is used to minimize evaporation of the Tungsten. Halogen lamps actually self clean - restore the filament but cant operate at reduced power for that reason. Halogen bulbs on a dimmer fail faster than at higher temperatures (full brightness)

Some History Thomas Edison's original electric light, introduced in 1879, was not very practical or efficient. The carbon filament in the lamp burned out easily and the lamp wasted electricity. It produced only 3.5 lumens per watt (lpw)-an efficiency of less than a quarter of a percent. Later filaments were made from metalized carbon or tantalum. These materials produced brighter illumination, but they were still very brittle.

In the early twentieth century, William Coolidge explored the metallurgy of tungsten. Tungsten is a notoriously brittle metal, but it evaporates slower than carbon when heated to high temperatures. (Higher temperatures produce brighter light and greater efficiency.) Coolidge developed a process to make "ductile" tungsten wire. In 1913, Irving Langmuir discovered that, by coiling the tungsten filament and placing an inert gas like nitrogen inside the bulb, he could increase the efficiency and the usable bulb life. Frosted bulbs and other modifications followed, but no dramatic improvements of the incandescent bulb occurred until "halogen" bulbs were developed in the 1950's.

Answer 3

Tungsten apparently has very high melting point and as we all know the filament used is very thin such that the resistance is so high that it gives out heat with light. If the filament snaps due to heat, the connection will break and the bulb will diffuse. To stop that from happening, Edison used tungsten. Why the vaccum?? To avoid oxidation of tungsten. Presence of air can cause oxidation and gradual deterioration of the metal, causing it to snap. Thus, to avoid that phenomenon, vaccum is used.

Answer 4

If it were not in vacuum, the tungsten would burn up rapidly. When first turned on, the resistance is very low, almost a dead short. The tungsten heats up very rapidly and the resistance goes much higher. Most bulbs burn out when turned on because of this. It is best to leave expensive things like computer and TVs on while you are around and not turn them off and on for the same reason. These expensive things don't give off much heat and do not consume large amounts of power.

Answer 5

Edison tested many materials to emit light in light bulbs. He found that having the material in a vacuum prolonged the life of the materials.

Answer 6

Kirk M and Firestorm were right. The original successful filament discovered by Edison was nothing but a strand of thread off his coat, i.e. carbon based material.

The rest are as what Kirk M and Firstorm described.

Answer 7

Without the vacuum the tungsten would combine with oxygen in the air and oxydize and consume the filament.

Answer 8

Because Toungston is one of the toughest metals with one of the highest melting points, yet very ductile and not soo costly. Best choice...

Answer 9

I agree with the first answerer. W was discovered suitable after him because it has the highest melting point among all metals.

Answer 10

Air contends oxygen and moisture, this will cause corrosion on the wire, this severely shortens the burning time of the wire.