What is Power
By Diana Gosper
I want more power!
I want free power!
I want reliable power!
But what is power? It can't just be the 230 V plug on your wall right? Right.
Power (represented by the symbol P) is basically a calculation of the workload that an electric current can do, and that workload is measured in watts.
There is a formula for calculating power but first we need to look at a couple of other basics.
I mentioned the electric current; ampere (amp for short), represented by the letter A, is how an electric current (represented by the symbol I) is measured; the current itself is being created by the movement of electrons within a conducting material of some sort (the conductor).
Something has to push those electrons though right? Right. The force that makes the electrons flow is called voltage and is a pressure measured in volts and the symbol is V (also referred to as U in Europe).
As the electrical current is being forced through the conductor, it meets resistance, and that resistance is measured in ohms, the symbol is Ω.
Voltage, current and resistance are related in a directly proportional relationship;
- if resistance is low, more electrons move, meaning a higher current.
- if resistance is higher, less electrons move, meaning the current is lower.
- if resistance is very high, no electrons move at all, meaning no current will be produced.
So in short, the resistance of the conductor is what determines how much current runs through a material- at a given voltage. This is called Ohm's Law and is represented in this formula for you techy geeky types;
Current (A) = Voltage (V) / Resistance (Ω)
I = V/R
Ohm's law is the most important law of an electrical circuit as it lays the foundations for almost all electrical calculations; it allows you to determine the current that runs through a cable (or a fuse) at different voltages. Knowing how much current you can run through a cable enables you to select the right cable for your system.
Now that we have the basics, I can give you the formula for calculating power;
P = I x V or Power = Current x Voltage
But also from Ohm's law other formulas can be calculated; one often used formula is;
I = P/V or Current = Power / Voltage
By the way, RPC still sells digital multimeters.