Now most electronic devices have their power usage info on them. Light bulbs usually have them on the bulb. Computers on the back of the power supply. It’s usually written on the brick that you plug into the wall when you charge your phone.

Lets just jump right in.  Take this 60W, 120V bulb on my desk(I don’t like florescent lights for desk work)  If I wanted to convert to amps I would simply  divide watts by volts.
60W/120V =  .5A

YEAH it uses .5A of power but that’s NOT what you’re getting billed for.  You get billed in Kilowatt hours.  So you have to add some time period.  
60W * 1 Hour = 60 WattHours = .06KWh

Now if we know that our electric company charges $0.10 a KWh
.06KWh * $0.10 = $0.006 an hour (or 1 penny cause you KNOW they’ll round UP) to run this 60W bulb for one hour.

Ok now for the formulas in a bit more organized format;

• Convert Watts and Volts To Amps 
  W / V = A
• Convert Amps and Watts to Volts
  A * W = V 
• Convert Amps and Volts to Watts
  V / A = W
• Convert Watts to WattHours (Wh) (T is time in hours)
  W * T = Wh
• Convert Wh to KWh
  Wh * 1000 = KWh
• Get the cost of our electrical appliance over time (R is your utility Rate)
  (W * T / 1000) * R = Cost

From this we can figure out pretty much the electrical cost of almost anything in our hour from looking at the little numbers on the back or bottom of the device.

The term electricity can speak about a wide range of things but for the most part when talking about conservation and the power in our house we’re talking about an electric current.  Electric current is when charged particles (most often electrons) move.   In a conventional current electrons move from the most positive to the most negative charge.  

Before I get too much farther it helps to think of electric current as water flowing through a hose.  Technically there’s a bit more to it but for this case we’re pretty much ok.

When electricity travels through something such as a wire it’s call conduction.  A related term is conductor which is the material that the current is passing though.  Different materials have different resistance to letting electricity through.  Most metals and water as you probably know are GREAT conductors while rubber and plastic are not.  Think of the empty place in the middle of the hose where the water goes through as the conductor.  

There are two types of current in peoples houses,  direct current (DC) or alternating current(AC).  DC is what comes from batteries or the black boxes you often see on phone chargers.  DC moves in one direction.  AC is what we get from the outlets in our house.  AC current moves back and forth never really getting anywhere (i.e. two steps forward two steps back). 

There are several terms used to measure electric current.  Each are related to the other and can be converted quite easily.

The first is ampere or amp.  You can often see this listed on electrical devices by a number and an A.  The actual technical definition of an amp is pretty complex but simply put an amp is a certain amount of electrical current.  The average home usually has about 100A service.  This means that you can pull 100A  of power at a time(TIME is a factor in this).    An amp would be the equivalent of gallons per minute in our hose. 

Next is a Volt(V).  A volt is the potential difference that the electric charge must have to do something.  With the hose it would be the pressure of the water in the hose.  Low voltage = Low Pressure.  

A Watt(W) is the amount of energy used or the amount of push needed to run something or the amount of amps(gallons per minute) multiplied by the volts(pressure).  If you think of a water wheel at the end of the hose, volts would be how much water at what pressure would turn it.  If you dump a LOT of water slowly or a little water under high pressure the wheel will turn.   

Now your electric company sells you power using Kilowatt Hours.  This is the amount of work(1,000 watts) over time(hours).  This would be the amount of spinning the water wheel does over time.

Finally there is the term Hertz which is a measure of frequency and is only used for Alternating Current(AC).  This is the amount of times that something goes back and forth in 1 second in this case the direction of the current.   In North America we use 60Hz most of the rest of the world uses 50Hz.   

So there you have it a bunch of terms about electricity.  In a future post I’ll go over using these terms and measurements to convert and measure your electrical usage.