I am just getting started in electronics. I have been looking at voltage in parallel DC circuits and using the water analogy of pressure for voltage and flow of water for current . Say I have a simple circuit starts with 9 volts and goes to a resistor of say 50 ohms now it splits into a parallel with two resistors one at say 100 ohms and the other at 5 ohms - ok its easy enough to calculate the voltage drop across that system - but here is what I find confusing - say I keep ramping up the 100 ohm resistor - ok its going to use more and more voltage - if i replace it with say 5 Mohm its going to use up most of the voltage. The water analogy would be the pipe is getting smaller and smaller. Now replace it with 500Gohm - ok again even more of the voltage is used up the pipe is getting extremely small - so lets just keep making the pipe smaller and smaller and smaller - it keeps using up more and more voltage ... we keep making it smaller now only a few molecules of water get through it has a huge resistance - now only one water molecule can get through the pipe - monstrous resistance now none can get through and the resistance drops to zero just seems odd that as we close down the pipe resistance gets higher and higher until its totally closed and then we have "no resistance" MY only answer is that we have no flow and if we have no flow (no current) that you cant calculate voltage - but if you let just one water molecule through then you have flow and voltage is used up
so to push millions of water molecule through ( ie low resistance ) you little voltage - to push thousands you use some voltage to push one one water molecule through you use up most of your voltage but to push none through you use no voltage
millions of water molecule ++++++++ less voltage used +
thousands of water molecules ++++ some voltage used ++++
one molecule + most voltage used ++++++++++
zero molecule 0 No voltage 0
In the left hand column the numbers go to zero if the right hand numbers head towards infinity - but as you continue the process they both drop to zero essentially destroying the patter that was developing
so to push millions of water molecule through ( ie low resistance ) you little voltage - to push thousands you use some voltage to push one one water molecule through you use up most of your voltage but to push none through you use no voltage
millions of water molecule ++++++++ less voltage used +
thousands of water molecules ++++ some voltage used ++++
one molecule + most voltage used ++++++++++
zero molecule 0 No voltage 0
In the left hand column the numbers go to zero if the right hand numbers head towards infinity - but as you continue the process they both drop to zero essentially destroying the patter that was developing