junction
Definition
A junction is a point where two or more conductors meet. Junctions are important in electrical circuits because they allow current to flow from one conductor to another.
There are two main types of junctions:
- Ohmic junctions: Ohmic junctions are junctions where the current flows smoothly from one conductor to another. This is the type of junction that is most commonly used in electrical circuits.
- Non-ohmic junctions: Non-ohmic junctions are junctions where the current flows in a more unpredictable way. This type of junction is often used in electronic devices, such as transistors and diodes.
Junctions are an important part of electrical circuits. They allow current to flow from one conductor to another, which is essential for the operation of many electrical devices.
How can the word be used?
The traffic was backed up at the junction.
Different forms of the word
Noun:
- A junction is a place where two or more things meet or join. For example, a railway junction is a place where two or more railway lines meet.
- A junction is also a point where two or more roads meet. For example, a traffic junction is a point where two or more roads meet.
Adjective:
- Junction can be used as an adjective to describe something that is connected to or joins two or more things. For example, a junction box is a box that contains electrical connections between two or more wires.
Verb:
- Junction can be used as a verb to join two or more things together. For example, the electrician junctioned the two wires together.
Etymology
The word "junction" comes from the Latin word "jungere", which means "to join". It first appeared in English in the 14th century.
The word "junction" can be used to refer to a physical place where two or more things meet or join, such as a railway junction or a traffic junction. It can also be used figuratively to refer to a point where two or more ideas or concepts meet or join, such as a philosophical junction or a scientific junction.
Question
Where might you find a junction?
AQA Science Exam Question and Answer
Question:
What is a junction in the context of electronics, and how does it influence the behaviour of electronic components? Explain the significance of junctions in the operation of diodes and transistors in electronic circuits.
Answer:
In electronics, a junction refers to the point where two different types of materials meet within a semiconductor device. Junctions are crucial as they determine how electrons move within the device, impacting its overall behaviour.
Junctions play a fundamental role in diodes, which are semiconductor components that allow current to flow in only one direction. The junction in a diode consists of a p-type semiconductor (electron-deficient) meeting an n-type semiconductor (electron-rich). This junction creates a barrier that prevents electrons from moving across it in one direction, effectively enabling the diode to act as a current valve.
Transistors, another essential electronic component, have multiple junctions. Bipolar junction transistors (BJTs) have two junctions, while field-effect transistors (FETs) have one. Transistors amplify or switch electronic signals. By applying a small current or voltage at one junction, the flow of a larger current or voltage can be controlled at another junction.
The significance of junctions lies in their ability to manipulate electron flow, enabling the creation of complex electronic circuits. By exploiting the properties of these junctions, electronic engineers can design devices that perform tasks ranging from signal amplification to digital logic operations. Understanding how junctions influence electronic behaviour is fundamental for designing and optimising the performance of various electronic components and circuits.