For many conductors of electricity, the electric current which will flow through them is directly proportional to the voltage applied to them. The ratio of voltage to current is called the resistance, and if the ratio is constant over a wide range of voltages, the material is said to be an "ohmic" material.
( I ) Current is what flows on a wire or conductor like water flowing down a river. Current flows from points of high voltage to points of low voltage on the surface of a conductor. Current is measured in (A) amperes or amps.
( V ) Voltage is the difference in electrical potential between two points in a circuit. It's the push or pressure behind current flow through a circuit, and is measured in (V) volts.
( R ) Resistance determines how much current will flow through a component. Resistors are used to control voltage and current levels. A very high resistance allows a small amount of current to flow. A very low resistance allows a large amount of current to flow. Resistance is measured in ohms.
( P ) Power is the amount of current times the voltage level at a given point measured in wattage or watts.
Ohms law, sometimes more correctly called Ohm's Law, named after Mr. Georg Ohm, mathematician and physicist b. 1789 d. 1854 - Bavaria, defines the relationship between power, voltage, current and resistance. These are the very basic electrical units we work with. The principles apply to a.c., d.c. or r.f. (radio frequency).
Real time physics simulation showing Ohm's Law relationship, V=IR. Ohm's Law defines the relationship V = IR
The law can be stated thus: 'The intensity of a current passing through most materials is directly proportional to the potential difference applied across the material'.
This is represented by the formula:
V = IR
where V is the potential difference, I is the current, and R is a constant called the electrical resistance of the conductor. The potential difference is also known as the voltage drop, and is sometimes designated by E or U instead of V.
The SI unit of current is the ampere; that of potential difference is the volt; and that of resistance is the ohm, equal to one volt per ampere.