Friday, September 16, 2011

Resistance is not futile.

Resistance is not futile, no matter what that infamous collective would have you believe.  This is just their propaganda machine lowering the resistance of their foes.

Hang in me, you get a couple short paragraphs of electronics context before the good stuff.

What is resistance?  In the world of electronics, it is an inverse measure of the conductivity of a material.  It is measured in "Ohms."  Conductivity is measured in "Mhos" how cute.  Resistors are electrical devices that are created to give a specific resistance within a specified tolerance.  Resistores are available ranging from milliOhms to MegOhms, quite a few orders of magnitude.  Resistors are critical to the proper operation of nearly every electronic device, gadget and system we use on a daily basis.

There is one electrical system where any resistance is extremely detrimental to proper operation.  The starter motor on a car.  One ohm of resistance will cause the entire system to fall on its face.  Such a little amount of resistance, how does this happen?  Lets take a super quick hopefully painless look at Ohms Law.  E=I*R.  E is the Voltage drop across a conductor, I is the current flowing through, R is the resistance.  In a car starter the object is to get as much power from the battery to the starter as possible.  so if we have one Ohm of resistance how much power will that steal from the system?  We can figure this out from some things we know.  A typical car starter will draw 100-200 amps while starting the car, we will go with 100 amps.  Drawing 100 amps through a 1 ohm resistor will drop voltage by 100 volts (I think this would use up approximately 1.21 jigawatts.)  Oh we start from 12 volts.  Thats where things get complex.  Lets go with one tenth of an Ohm of resistance, now we are only dropping 10 volts.  Leaving 2 volts for the starter. We need another equation P=I*E, the PIE equation (makes me hungry) Power = Current * Voltage.  That gives 1000 watts going to the resistance and 200 watts left for the starter.  Guess what?  The car is not going to start!  Where does this resistance come from?  Usually loose battery terminals or corrosion somewhere, been there done that.

Good you made it through the mumbo jumbo.  How does this apply to you?

Resistance can come in many forms and in many places.  Office place resistance, boss says prepare the TPS reports, it is natural to respond with a little resistance.  This is a low current request, so even a lot of resistance will not generate a lot of wasted effort or extra heat.  Two year old resistance, ask any two year old to do anything, will will find out what two year old resistance is.  Teenager resistance, see two year old resistance.

At times resistance is a good thing.  We are assigned a test and hesitate to do it.  We mull it over and eventually decide on the best course of action and the product is better for the resistance.

Some times resistance is very bad.  A high current system must transfer as much power to the end result as possible.  Like a car starter any resistance is likely to stop the entire project dead in its tracks.  A business startup is like this as much energy as possible needs to transfer to the end product.  A little corrosion in the line, such as an uncooperative business partner, non-availability of food money or stiff regulations.  Will make it very difficult to get started. 

Resistors when connected in parallel lower the over all system resistance.  If you see a system where someone is being a resistor you can choose to short-circuit the system to make things happen.  You see where someones lack of experience is slowing down a project and you pitch in.  This is something to feel good about.  It is also a time to be careful.  Like a two year old that will not learn to tie his shoes if you keep doing it for him, people will keep needing a bailout if you keep bailing them out.  I think this is where the old saying about giving fish and teacking how to fish applies.

At times people will be the resistance on purpose, and out of spite.  Please try to recognize if you are doing this yourself, please try to help people along if possible, or at least to not cause them resistance along the way.

If you want more on this let me know, I have some thoughts on internal resistance.

Thanks for reading,


No comments:

Post a Comment