In the reverse direction, as the potential difference is increased across the diode very little current flows across the junction, although it does increase slowly. However a point is reached where breakdown occurs and current flows.
The overall characteristic of a PN junction diode is far from Ohmic as seen in the characteristic below. The PN junction diode is the most basic form of semiconductor device. Consisting of a single junction between P-type and N-type material it is able to act as a rectifier allowing current to pass in only one direction. Read more about PN Junction Diode. Most semiconductor devices: The semiconductor diode is a specific example of a semiconductor device that is often encountered within electronic circuits.
However it is not the only example of a non-Ohmic conductor made from semiconductor material. Most other semiconductor device are good examples of non-Ohmic responses. It is not possible to detail each type, but it is probably sufficient to mention that they are non-Ohmic in many if not most of the aspects of their operation. These are just three examples of non-Ohmic conductors and components.
There are various other types which can be encountered. Varistors are but one example. These are used for protecting against mains power or line transients. Normally they have a high resistance, but when a certain voltage is exceeded, the resistance falls so that they absorb the transient and protect the units being powered.
Ohmic and non-Ohmic conductors as well as electrical and electronic components are found in all areas of electrical and electronic science.
Both types of conductor are used, and their individual properties are put to specific uses to provide the wealth of capabilities that are needed to support modern day electrical and electronic circuit design, components, and systems. It is surprising what a variety of ways in which these different characteristics can be used. Conductors and electronic components that follow this law are called Ohmic conductors, whereas others are called non-Ohmic conductors The Ohmic conductors may also be called linear electronic components, whereas the others are non-linear as they do not have a linear relationship between voltage and current.
Main examples of Ohmic and non-Ohmic conductors There are very many examples of both Ohmic and non-Ohmic conductors. Ohmic conductors definition: Ohmic conductors are those electrical conductors that follow Ohms law. Non-Ohmic conductors definition: Non-Ohmic conductors are those electrical conductors that do not follow Ohms law. Read more about. Why a Filament Lamp is Non-Ohmic. If the current given is low, then a milliammeter is used. However, for voltage, the voltmeter is used and is connected in parallel.
It measures the voltage or potential difference in volts. The battery or cell provides an electromotive force. This force pushes the electrons into the circuit. From this perhaps we can understand that when the voltage increases, the amps also might increase. From the readings of these two components, graphs are drawn. When we have to check if the certain substance conducts we can place it in a circuit. When a metal is placed in the circuit, an electric field is created.
This electric field has charges and these charges have forces on them. So the electrons are accelerated and gain velocity and energy. They will collide with atoms that are vibrating in their lattice site and give some of their energy to it. When they slow or stop the energy is again provided to them by the electric field and they accelerate. The charges thus move to one side and this called a current.
The circuit that can be used should consist of a power d. The bulb is used to show whether the substance conducts or not. If correct accurate reading regarding the current and the voltage has to be taken, then the ammeter is connected in series and the voltmeter in parallel. This way we will know how much current is flowing through the circuit if the object is a conductor. If the object is an insulator then the bulb will not light up and the ammeter will not show any reading.
This is a conductor when no potential difference is applied. When a potential difference is applied between the ends of the conductor, as shown in the previous circuit, they all line up to move to one side. This is the structure after the potential difference is applied. The resistance in metallic conductors increases as temperature increases. The resistance increases because the atoms of the metal start to vibrate and so making it difficult for electrons to pass through.
This increases resistance. So whatever the amount of electrons provided, the current will decrease because the resistance has increased. In semiconductors the conductivity varies from the types of semiconductors. There are two types intrinsic and extrinsic semiconductors. This way there is no definite rule for these materials. So this would have to be seen only when I deal with the semiconductors separately.
Silicon and germanium are semiconductors. Semiconductors are materials in which the amount of current increases with temperature. So this means that they are better to use if the temperature is high. Since we have now discussed the conductivity of certain substances and the free electron theory, I would now like to introduce the ohmic and non ohmic conductors.
Some other factors also affect the ohmic conductors. There are normally two types of conductors. The two types of conductors are ohmic and non ohmic. Conductors such as pure metals are ohmic conductors. In this case the ohmic conductors have to be kept under constant pressure and constant temperature for them to behave as ohmic conductors. The resistance does not vary according to the current, it remains constant.
In metals, there are free electrons that are responsible for carrying current. These free electrons vibrate and often collide with each other and also with electrons of nearby atoms thus releasing kinetic energy. When this energy is lost as heat, it makes it difficult for the electrons to pass through and the resistance of the metal increases with increased temperature.
This is when the conductor becomes a non Ohmic conductor. For example, tungsten that is used in a filament bulb is a Ohmic conductor and allows for passage of current but becomes a non Ohmic conductor when its temperature increases and it begins to glow.
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