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Introduction
Ohm’s law states that the current flowing through the conductor is directly proportional to the potential difference across the terminal. The conductors that follow Ohm’s law are known as ohmic conductors, whereas conductors that do not follow Ohm’s law to a great extent are known as non-ohmic conductors.
Conductors are those materials through which current can flow easily. While designing the electrical device, it becomes essential to check whether the conductor is ohmic or non-ohmic. We aim to provide study material notes on the V-I characteristic of ohmic and non-ohmic conductors.
What are conductors?
Any material that allows the transfer of heat and current through them is known as conductors. All those materials that have free electrons or ions are able to conduct electricity. Free electrons are used for those electrons that are very far from the nucleus and can easily detach themselves from the atom. Their motion is responsible for the flow of current. Examples of conductors are iron and steel.
The conductors that have high amounts of free electrons are known as good conductors. At the same time, those who conduct electricity in very feasible amounts are known as bad conductors. Some materials do not conduct electricity, they are known as insulators. Examples of the insulator are wood and rubber.
Ohm’s Law
Ohm’s Law was put forward by George Ohm in 1789. According to this Law, the current that flows through the circuit varies proportionally to the voltage difference across the terminal of the cell.
V ∝ I
V = IR
Here, R is the constant known as resistance. It is the obstruction created by the flow of current. The unit of resistance is Ohm. It increases with the temperature with the length of the wire and decreases with the increase of the area of the wire.
On plotting the voltage and current on a graph, we get the graph as shown below. We get a positive and straight slope, thus indicating a constant increment of current with the voltage.
Ohm’s Law is one of the most significant laws in electricity. For studying the behaviour of electric circuits, Ohm’s Law is one of the most widely used rules.
However, not all conductors strictly follow Ohm’s law. Various conductors show variations and do not have a straight slope for the V-I graph. In this article, we will be studying about V-I characteristics of both ohmic and non-ohmic conductors.
Ohmic conductors
Ohmic conductors are those conductors that strictly follow Ohm’s Law; that is, the voltage varies linearly with the current. Examples of ohmic conductors are silver and resistors.
Non-ohmic conductors
The non-ohmic conductors are those conductors that do not strictly adhere to Ohm’s Law. Examples of non-ohmic conductors are semiconductors and electrolytes.
V-I characteristic of ohmic and non-ohmic conductors
The V-I characteristic of any conductor is obtained by plotting the graph between voltage and current. The voltage is plotted on the y-axis and the current is taken on the x-axis. By changing the potential difference, the current will also change. We take different values of V and I to obtain the V-I characteristic of the conductor.
Ohm’s law states a linear relationship between voltage and the current. All the conductors that follow Ohm’s law are known as ohmic conductors. These conductors have a linear graph of V-I, as shown in the diagram below. Thus, ohmic conductors are also non-linear components.
The non-ohmic conductors do not follow Ohm’s law to a great extent. Initially, they may follow the linear graph, but ongoing further, the graph becomes a non-linear relationship of voltage and linear—for example, incandescent light bulbs and semiconductor devices.
Comparison Table Between Ohmic and Non-Ohmic Conductor
Parameter of Comparisons | Ohmic Conductor | Non-ohmic Conductor |
Definition | Conductors which follow ohm’s law that is current vary proportionally to potential differences. | The conductors which do not follow Ohm’s law are known as non-ohmic conductors. |
Relationship between current and voltage | There is a linear relationship between current and voltage. | The current and voltage have a nonlinear relationship. |
The slope between current and voltage | The slope is positive with a straight line. | The slope is a curved line. |
Effect of temperature | With the increase of temperature, the ohmic conductors start behaving as non-ohmic conductors. | The resistance varies as per the change in temperature. |
Examples | Metal, resistor, nichrome wires. | Semiconductors, electrolytes. |
Conclusion
Ohm’s law is one of the most used and essential rules in electronics. The law states that the voltage and current are proportional to each other on increasing the voltage, the current also increases. Conductors are the material that allows the flow of electric current through them. Based on Ohm’s law, there are two types of conductors, one ohmic conductor and the other non-ohmic conductor.
We read about both types of conductors in this article. This study material notes on ohmic and non-ohmic conductors provide complete knowledge of the topic.
