.gif)
Node (circuits)
Encyclopedia
In electrical engineering
, node refers to any point on a circuit where two or more circuit elements meet. For two nodes to be different, their voltages must be different. Without any further knowledge, it is easy to establish how to find a node by using Ohm's Law
: V=IR. When looking at circuit schematics, ideal wires have a resistance of zero. Since it can be assumed that there is no change in the potential across any part of the wire, all of the wire in between any components in a circuit is considered part of the same node.
Voltage = Current * Resistance
since voltage is a measure of potential difference the voltage between any two parts of the same node is:
Vab= (Current) * 0
So at any two points on the same node, the change in potential difference is 0. Therefore, throughout the entire node the voltage is the same.
In this circuit diagram
the voltage in the green node is the same throughout, likewise, the voltages in the blue node and the red node are the same throughout.
In most cases, the voltage difference between one point on a piece of metal (such as a copper wire), and the voltage at another point of the same piece of metal or on other bits of metal with metal-to-metal contact with the first piece of metal, is so small that it is usually considered insignificant.
So every bit of that connected metal can be considered part of the same node.
Some notable exceptions, where the voltage difference is large enough to become significant, include:
Electrical engineering
Electrical engineering is a field of engineering that generally deals with the study and application of electricity, electronics and electromagnetism. The field first became an identifiable occupation in the late nineteenth century after commercialization of the electric telegraph and electrical...
, node refers to any point on a circuit where two or more circuit elements meet. For two nodes to be different, their voltages must be different. Without any further knowledge, it is easy to establish how to find a node by using Ohm's Law
Ohm's law
Ohm's law states that the current through a conductor between two points is directly proportional to the potential difference across the two points...
: V=IR. When looking at circuit schematics, ideal wires have a resistance of zero. Since it can be assumed that there is no change in the potential across any part of the wire, all of the wire in between any components in a circuit is considered part of the same node.
Voltage = Current * Resistance
since voltage is a measure of potential difference the voltage between any two parts of the same node is:
Vab= (Current) * 0
So at any two points on the same node, the change in potential difference is 0. Therefore, throughout the entire node the voltage is the same.
Circuit diagram
A circuit diagram is a simplified conventional graphical representation of an electrical circuit...
the voltage in the green node is the same throughout, likewise, the voltages in the blue node and the red node are the same throughout.
In most cases, the voltage difference between one point on a piece of metal (such as a copper wire), and the voltage at another point of the same piece of metal or on other bits of metal with metal-to-metal contact with the first piece of metal, is so small that it is usually considered insignificant.
So every bit of that connected metal can be considered part of the same node.
Some notable exceptions, where the voltage difference is large enough to become significant, include:
- high-precision resistance measurements using four-terminal sensingFour-terminal sensingFour-terminal sensing , 4-wire sensing, or 4-point probes method is an electrical impedance measuring technique that uses separate pairs of current-carrying and voltage-sensing electrodes to make more accurate measurements than traditional two-terminal sensing...
Kelvin connection - the difference in voltage between ground and neutralGround and neutralSince the neutral point of an electrical supply system is often connected to earth ground, ground and neutral are closely related. Under certain conditions, a conductor used to connect to a system neutral is also used for grounding of equipment and structures...
, between the "neutral wire" and the "safety ground in a domestic AC power plugs and socketsDomestic AC power plugs and socketsAC power plugs and sockets are devices for removably connecting electrically operated devices to the power supply. Electrical plugs and sockets differ by country in rating, shape, size and type of connectors...
, can be fatal. A properly installed electrical system connects them together at one (and only one) location, leading many people to the fatally incorrect conclusion that they are at "the same" voltage, or that the safety ground is "redundant and unnecessary". - the Seebeck effect and the Peltier effect
- joints involving aluminium wireAluminium wireAluminum wire is a type of wiring used in houses, power grids, and airplanes. Aluminum provides a much better conductivity to weight ratio than copper, and therefore is used in power wiring of some aircraft....