To understand exactly what some of the common SI / metric units actually are, it is often useful to have a definition.
The SI units have exact definitions, and in this way those using them know exactly what they are. This applies to electrical and electronic associated SI units such as voltage, current and resistance, as much as the general ones like length, weight and the like.
Electronic unit definitions
Definitions for the more widely used electrical and electronic units are included below:
- Coulomb: A coulomb is the quantity of electricity transported in one second by a current of one ampere.
- Farad: One farad is the capacitance between the plates on a capacitor when the quantity of one coulomb of electricity produces a potential difference between the plates on one volt.
- Henry: The definition of a henry is the inductance of a closed circuit which produces an EMF of one volt when the current varies uniformly at one ampere per second.
- Hertz: A Hertz is the frequency of a periodic phenomenon of which the time period is one second.
- Joule: The definition for a joule is the work done when the point of application of a force of one newton is displaced through one metre in the direction of the force.
- Newton: The definition for a newton is that force which gives a mass of one kilogram an acceleration of one metre per second squared.
- Ohm: The definition of an ohm is the resistance between two points of a conductor when a constant potential difference produces a current of one ampere.
- Volt: The definition for a volt is the potential difference between two points of a conductor carrying a constant current of one ampere when the power dissipated in the conductor is one watt
- Watt: The definition for a watt is one joule per second
- Weber: A weber is the flux which, linking a circuit of one turn, produces in it an EMF of one volt as it is uniformly reduced in one second.
These are some of the definitions for some of the more widely used electrical and electronic units. It helps to have a broad understanding of what they are when using them so that a concept of the magnitude, etc can be gained.