Posted by 2500 ug. Club (11/30/11 12:37 PM)

Hello fellow shrommies...


I will occasionally post math formulas that might be relevant to our hobby.

I have over 10 years teaching electronics, physics and other stuff @ the Pre, grad, and post grad level...

 Lets start... :)  I would venture to guess that most of us would like the basic concept of this term power, its units of measurements, and how to calculate power consumption.

First there is True power, effective power, and reactive power..

Lets focus on true power first.... The unit of measurement of power is the Watt .

Basically true power is the amount of electrons that flow past a given point of resistance (  resistance of current flow )  in one second.

To calculate true power you will need to know two out of 3 variables, those being Voltage, Current or Resistance.

So if you know the voltage and current you simply multiply the two values to calculate true power.. I.E.  P= V X I


Lets try a practical problem.. You have 110 volts RMS and are drawing 2.5 Amperes of current..Your power would calculate 110.0 volts times 2.5 amps = 275.0 watts RMS*. ( P= 110.0 x 2.5 = 275.0 )

The 3 most commonly used formulas are such....

1) P= I x V  (the above example)

2) P= E^2 / R *

3) P= I^2 x R


Lets try example #2... You have 220.0 V and a resistance of 50.0 Ohms. You would square the voltage and divide by the resistance of 50 Ohms.. 220.0^2 / 50.0 = 968.0 watts of power.


* RMS is the most used ( needed)  value to calculate power for shroomer peeps..... :)

* when I use the ^ symbol it indicates to the power of "X" or any rational number.     I.E.  2^1.5  = 2.828426.

I like to explain where these units of measurments came from..

The Watt is named after a chap named James Watt.

The Ohm (Unit of measurement for resistance) is named after a chap named Simon Ohm.

The Volt was named to an old fart named Volta...

Lastly I will always use units of measurement..unless it is a "pure" number...these pure numbers we call figure of merits, O.K.?

If it has a unit of measurment I will always use the correct unit...

 Q:  What type of calculator does the shroomy need?....

A: I use a TI-36X solar. They retail for under $20.00 U.S. and are word every penny IMHO...


As an instructor if you see a mistake please correct me.....I really do, or we, always need to transmit correct information!


P.S. ferget spell'in,,,I cain't spell worth a tinkers damn..... :)