The road to electrical lighting

In this post, I want to share my understanding of lamps today as I know it. Am not a genius at this but neither are most people so please read along.
Let me first talk about lighting in general, mankind for ages has sought for a way to light up his home when the sun goes down. If we look back at where we have come from as a species, our ancestors rubbed stones together and made a fire. With this fire, they were able to torch pieces of wood to give them light. They not only used it for light but they also needed it for heating during cold nights. Fast forward later, there was the invention of wax. A thin thread-like strand called a wick was fitted along the centre of a cylindrical block of wax to make a candle. Candles were better than the wooden torches as they were more mobile and reliable than their predecessors. You could take a candle with you anywhere, keep it anywhere and never be worried about it having been wet by the rain. You didn’t need to build a dedicated fireplace for it in case of indoor lighting. However the candles never really replaced wood torches as they didn’t give as much heat to keep people warm.

Fast forward later, we invented the kerosene lantern. This was an amazing invention of its time. It even had brightness adjustment. Relative to the others, it was much safer and cleaner and brighter. The kerosene lantern worked on a simple principle. there was a wick that was dipped in a flammable fuel know as kerosene. This wick sucked on this fuel gradually and if it had been socked just right, it would burn at the top for as long as it is still dipped in fuel without completely getting burnt itself. Seems like magic right? yeah back then it was. So the lantern was a mechanical structure built around this wick that had compartments for holding the kerosene, adjusting the height of the wick and hence adjusting the brightness of the flame. A transparent bulb that housed the flame and protected it from external winds. Ventilation to let oxygen into the lamp to facilitate burning and mechanical arms for holding and moving it around. It was amazing!!

Up to that time, the above inventions were made before the invention of the electric bulb by Thomas Edison in 1878. They all used an adiabatic flame formed from a combination of heat, fuels, oxidants and a chain reaction. The fuels used were mostly organic compounds like wood or wax. This flames needed a constant supply of fuels and oxygen to keep going and give light for as long as possible. The initial heat given to them would initiate the burning which would give light and heat and the presence of more oxygen and more fuel would re initiate the process again and again and the light continues forever. They seem to be good old times, but are they? They served our societies well, made night time social gatherings worthwhile as you could see who is next to you, but they were also recipe for fire hazards, burnt up homes, carbon monoxide poisoning and many other terrible things.
Some of these lighting systems(Lamps) were relatively safe and reliable but they all lacked one important aspect. They were not clean. Once the flame was burning there was constant CO2 release into the atmosphere, Once the light went out. You had to figure out where to put the ashes or dispose of the unburnt wax. Then With the invention of Electricity, a lot had to change.
Electricity recreated the whole way we approach lighting, for very many years most of the electric lamps we have made fall in four major lighting categories; Incandescent, Fluorescent, Electric Arc, Gaseous discharge Lamps and most recently LED lamps. The most common of all these to date are the incandescent lamps. These lamps work on the principle of electrical resistance.
From basic electricity knowledge, we know that when a voltage is applied across a conductor, a potential difference is set up and current flows through that material. The resistance of that material to current flow is the ratio of the voltage to the current through it. That means when you have control of the current or voltage then you have control over the resistance too, When you can control resistance then you can control temperature too. Once you can control how hot a body can get then you can control the heat and light it can emit too.
Material resistance, when a material’s resistance is changed it’s temperature changes too(get’s heated up). Talking of heating up, all hot bodies actually emit radiation at different wavelengths depending on their nature and temperature, that includes you and me. The secret source of an incandescent lamp is its filament, this filament usually made of tungsten or osmium when current goes through it, it get’s really heated up to temperatures of over 3000'C but it’s melting point is way much higher (3422'C) so it doesn’t melt or sublime it just gets pretty hot. At this temperature, it shall be radiating waves whose wavelength falls in the visible spectrum of electromagnetic radiation. This radiation energy is interpreted as visual sensation to the human eye giving us the holy grail, LIGHT.

Several inventions of the incandescent lamp had been made but not until Thomas Edison’s first most practical Incandescent lamp. Thomas Edison’s filament based incandescent lamp had the most practicability amongst all the other options that were there at the time. Carbon filaments were good, They had a high melting point of up to 3500'C but carbon would easily disintegrate after its operating temperature of 1800'C. Sadly, it also had a negative temperature coefficient, Which meant the more you heated it the lesser it’s resistance became which works in reverse sense of what actually makes a good filament. It also had a low commercial efficiency of 3–4.5 lumens per Watt(This mean it would be pretty dim). Then there was Tantalum which had a positive temperature coefficient but still had a low commercial efficiency of about 2 lumens per watt. Now Tungsten, had all A’s, It had a high operating temperature 2500'C-3000'C, It had a positive temperature coefficient, It also had a very high commercial efficiency of up to 18 lumens per Watt. It was bright, It was good and It was clean. So that was the face of Electrical lighting for some time. Incandescent Light bulbs are actually not that efficient because they convert less than 5% of electrical energy given to them to light. The rest is lost to heat.
Next time I will be sharing what I know about Fluorescent Lamps. Thanks for reading this far. If you enjoyed this Recommend it and leave me some feedback below.
