Ohm’s law states that the electric current is proportional to the voltage and is inversely proportional to the resistance. But Ohm’s law is not applicable for all the materials.
Following are the limitations of Ohm’s Law:
- Ohm’s law is not applicable for unilateral electrical elements like diodes and transistors as they allow the current to flow through in one direction only.
- For non-linear electrical elements with parameters like capacitance, resistance etc the voltage and current won’t be constant with respect to time making it difficult to use Ohm’s law.
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Examples of Limitations of Ohm’s Law
Examples where Ohm’s law is not applicable are given below:
- Diode is an example which helps in understanding the limitations of Ohm’s law. When the voltage versus current graph is plotted for a diode it is observed that the relation between voltage and current is not linear. This happens when the voltage is marked in the reverse direction such that the magnitude is fixed. It is seen that the current is produced in the opposite direction with a different magnitude.
- Consider a water volt-ammeter. It is an example of unilateral network and Ohm’s law is not applicable for such networks.
- Also, it is not necessary that all conductors obey Ohm’s law. There are semi-conductors such as Silicon and Germanium which don’t obey Ohm’s law and they are known as Non-Ohmic conductors.
Check the video given below to undestand the concept of Ohm’s Law in details.