Difference Between Ohmic and Non-Ohmic Conductors (With Table)

An important law to establish the relationship between current, voltage and resistance was given by Georg Ohm which was named as Ohm’s law which is given as follows- 

                                               V= I * R

Where V stands for voltage, I for current and R for resistance.

While designing the electrical devices it is important to keep in mind the ohm’s law such that the current and voltage of them are within specifications. One such device is a conductor that works on the relationship of current, voltage and resistance. An electrical device that is capable of passing a current through it is termed as a conductor.

Conductors are of two types namely, ohmic conductors and non-ohmic conductors. Ohmic conductors are the conductors that follow Ohm’s law that is their resistance remains the same on changing the current and voltage. Non-ohmic conductors are those that do not follow ohm’s law which means that their resistance changes with changing current and voltage.

The difference between Ohmic and Non-Ohmic conductors is that the ohmic conductors are the ones that follow Ohm’s law, that is, they have a constant resistance when the current across them is increased or the voltage in them is varied while non-ohmic conductors are those that do not follow ohm’s law, that us, their resistance varies with varying conditions of current, voltage and temperature.

Comparison Table Between Ohmic and Non-Ohmic Conductors

Parameter of ComparisonOhmic Conductors Non-Ohmic Conductors
Basic definitionThe ohmic conductors follow ohm’s law, which implies that the resistance of the conductors remains constant on varying current and voltage.The non-ohmic conductors do not follow ohm’s law, that means the resistance of the conductor varies on sharing current, voltage and temperature.
Relationship between current and voltageIn the ohmic conductors, the current and voltage are directly proportional to each other, that is, there is a linear relationship between current and voltage.In the non-ohmic conductors, the current and voltage are not directly proportional to one another, that is, current and voltage have a non-linear relationship between them.
The slope between current and voltageThe slope between current and voltage in ohmic conductors is a straight line.The slope between the current and the voltage in non-ohmic conductors is not straight but a curved line.
Effect on temperature variationsConductors follow ohm’s law when the temperature is in the range for which the conductor has been made but as the temperature increases, ohmic conductors also behave as non-ohmic conductors.In non-ohmic conductors, the resistance of the conductors varies according to the variation in the temperature.
ExamplesExamples of ohmic conductors are metals, resistors, nichrome wires, etc.Examples of non-ohmic conductors are diodes, semiconductors, electrolytes, thyristors, transistors, filament lamps, etc.

What are Ohmic Conductors?

The ohmic conductors follow ohm’s law implying that the resistance of the conductor remains constant while varying current and voltage. In other words, it can be said that the relationship between the current and the voltage is linear.

When plotted on a graph, the slope of the current and voltage for ohmic conductors comes out to be a straight line. One of the drawbacks of the ohmic conductors is that they lose their properties when they are operated in ranges other than specified. They can also malfunction if the current applied is out of range.

The examples of the ohmic conductors are metals, resistors, etc. When the current flows through the resistor, it is directly proportional to the voltage or it can be said that they have a linear relationship. 

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What are Non-ohmic Conductors?

The non-ohmic conductors are those which do not follow ohm’s law. Not following ohm’s law means that their resistance is variable, it varies according to the change in current, voltage of temperature. The relationship between current and voltage in non-ohmic conductors is not linear.

Graphically speaking, the slope of the current and voltage for non-ohmic conductors is not a straight line but it is a curved line. The properties of non-ohmic conductors also vary according to the change in temperature.

The examples of non-ohmic conductors are diodes, transistors, thyristors, electrolyte, semiconductors, etc. In filament lamps, if the voltage is continuously increased but the currents doesn’t increase beyond a particular value then it is said to be non-ohmic.

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Main Differences Between Ohmic and Non-Ohmic Conductors 

  1. Ohmic conductors are those conductors which follow ohm’s law while the non-ohmic conductors are the one that does not follow the ohm’s law.
  2. In ohmic conductors, the resistance of the conductor remains unchanged on changing the current and the voltage, on the other hand, in a non-ohmic conductor the resistance of the conductor changes on changing current, voltage or temperature.
  3. In an ohmic conductor, the current and voltage are directly proportional to each other which means they gave a linear relationship, on the other hand, in a non-ohmic conductor, the current and the voltage are not directly proportional to each other which means they do not have a linear relationship among them.
  4. While plotting the graph of current and voltage, the slope in ohmic conductors is a straight line whereas the slope in non-ohmic conductors is a curved line.
  5. Conductors follow ohm’s law only in the temperature range for which they are designed, they lose their properties when operated on a higher temperature which is more than the specified range while in non-ohmic conductors the resistance of the conductor varies with the varying temperature.
  6. Examples of ohmic conductors are metals and resistors while the examples of non-ohmic conductors are diodes, transistors, semiconductors, etc.

Conclusion

Both the conductors, whether ohmic and non-ohmic, have their specific functions and purposes. However, ohmic conductors may lose their properties when operated on different ranges so it becomes really important to study their properties before application.

References

  1. https://www.sciencedirect.com/science/article/pii/002230937290227X
  2. https://www.tandfonline.com/doi/abs/10.1080/14786445008560976