The equations for ohm's law is the basic equation for electricity. An understanding of Ohm's Law is necessary for any understanding of electricity, batteries, alternative energy, your light bill, electronic construction etc.
Ohm's Law is very simple to understand if it is explained in basic terms. Most study in any field of science starts out with the understanding that one is going on to be a scientist so very highly technical term and concepts are presented to the student assuming he or she has the back ground to understand these terms and concepts. But what if you just want to understand the basics of electricity? Well, here we will explain electricity in a manner that doesn't require one to have a degree in physics.
Ohm's Law - The Formula
V = IR --- I = V/R --- R = V/ I
Anything that has to do with electricity has these three components.
Voltage = V, Current = I, Resistance = R
This formula can also be viewed as a triangle (see image)
What is Voltage?
Voltage can best be explained by referring to a water hose. Voltage is the pressure of the water in the hose. Not how much water in the hose but the pressure pushing on the water in the hose. We have all seen movies where a fire hose is used to push people back. A fire hose has a great amount of pressure on it. It's like the the wall socket in your house powered by a power plant. Touch it and your going to get knocked over.
Your garden hose is not going to knock any one over it's like the battery in your car.
Your car battery is most likely 12 volts, your wall socket is around 220 volts.
Voltage is measured in Volts.
The symbol for Volts is " V "
What is Current?
Current, lets say, is the amount of juice in the hose. Say you have that same fire hose with all the high pressure but you had foam mostly filled with air coming out, people would be laughing and having fun as they were sprayed. But say you had rocks spewing out of the hose, that would be a different story.
Current is what kills you when you get shocked.
Current is measured in Amperes, or Amps for short.
The symbol for current is " I "
What is Resistance?
Resistance is the friction opposing the flow of current. It slows the flow of current down. It reduces the voltage or pressure on the current. This is how an incandescent light bulb works. A current is passed threw a filament wire and the heat caused by the resistance of the filament causes the wire to glow. An example would be when you rub your hands together the heat from the friction causes your hands to heat up. Everything that an electrical current flows through has resistance. This resistance needs to be taken into account when building or fixing electronic equipment at home.
Resistance is measured in Ohms.
The symbol for Ohms is "Ω"
What are Watts?
Watts are a unit of measurement that is used to calculate the total power available or used by a system or item in the circuit. You calculate Watts by multiplying the volts time the current. For example, if your system is 12 volts and it is using 3 amps that would be 36 watts.
Watts are measured in Watts.
The symbol for Watts is " W ".
The formula for Watts is W = V x I
That reads Watts = Volts multiplied by Amps.
V = W / I ----- I = W / V
So if you had a 100 Watt light bulb in your house and 220 volts you now can figure the amps it is using.
I = 100 / 120 = .454 amps