In my business, I work with inventors and I frequently have to ask them to explain what is the "Novel Inventive Feature" of the their invention. I define this feature as that creative aspect of their invention that distinguishes it from everything that has already been invented (The Prior Art). However, getting this concept across is not easy, hence I thought it might be useful to take a lesson from a master of inventing Thomas A. Edison.
Every school child knows, if they know nothing more about Edison, that he "Invented the Electric Light". But what exactly was it that Edison invented. What was the "Novel Inventive Feature". Most people, those at least who have not read a biography of Edison, don't know that there were hundreds of inventors with their own version of the Electric Light working at about the same time as he. What was it that made his "Electric Light" unique.
In order to explain this I will need to introduce some very elementary concepts from Electrical Engineering. One of these is "Ohm's Law", which states that , Electric Current (I) ,which is analogous to the amount of water flowing through a pipe, is equal to Voltage (V) (the pressure needed to push the electrons through a resistive elemen, divided by Resistance (R) ,which is a measure of that property which seeks to prevent current from flowing through a resistive element . In algabraic terms this equation is written I=V/R.
Most of Edison's contemporary inventors thinking "inside the box" used as the filaments of their light bulbs, a low resistance wire. The current needed to light a 100 watt (P) bulb with a 1 ohm resistive filiament can be shown to be 10 Amperes from solving Ohms law since Power(P) = Current(I) * Voltage(V) which with some algaebraic manipulation leads to P=I^2*R and I = SquareRoot (P/R)] .
It doesn't take very many light bulbs (connected in parallel) drawing this much current to require very large diameter wires to supply a single household. To supply a city of many such households using these bulbs would have required electrical cables that were many feet in diameter.
Edison, realized this problem and decided to make a bulb with a high resistance filament , even though he had no idea how to make one. He knew that if the same 100 watt light had a 100 ohm filament it would need only 1 ampere to light. He actually went through over 2000 different filament designs before he found one that with the right resistance that wouldn't burn our quickly. [Experts will note this example is for Direct Current (DC) which is what Edison used. The analysis for Alternating current (AC) , that we use today is different and more complex]
So Edison's Invention wasn't really the Light Bulb, I was the high resistance light bulb, which made practical electrical distribution systems with wires of practical size. High Resistance was the Novel Inventive Feature of Edison's electric light.
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