For many conductors of electricity, the electric current which will flow through them is directly proportional to the voltage applied to them. When a microscopic view of Ohm's law is taken, it is found to depend upon the fact that the drift velocity of charges through the material is proportional to the electric field in the conductor. The ratio of voltage to current is called the resistance, and if the ratio is constant over a wide range of voltages, the material is said to be an "ohmic" material. If the material can be characterized by such a resistance, then the current can be predicted from the relationship:
Ohm's Law - I=V/R or Electric Current = Voltage / Resistance
You got that from my sig!
"I absorb energy like a sponge everywhere I go. It allows me to see the world and my purpose in it." Zak Bagans, Ghost Adventures (INFJ)
The binomial theorem & Pascal's triangle. It's the only time I have ever used advanced math in my career (software engineering) back around 1996. Which is why I put it #1.
I was an intern for a telecom company and the marketing department wanted to know how many of a certain type of circuit board to order. So someone gave the problem to the intern to play with for fun.
I instantly recognized it was some sort of common statistical problem. But rather than waste time figuring out which one and taking a lot of time assuring it was correct, I wrote a quick software program to simulate the entire statistical problem. Then once I had the stats that I knew were right, I noticed they fit a certain pattern. And so then I reverse engineered and saw they fit the Pascal's Triangle\binomial theorem or something like that.
So of course, I told my boss I solved it via the binomial theorem and Pascal's triangle and went through the formula showing it to him. And told him that I double-checked the work afterwards via a software simulation to prove it. That was a fun day for a 20 year old.