Ohm's Law

The amount of current flowing through any resistor is directly proportional to the amount of voltage applied across its ends.

V ∝ I

Ohm's law is a fundamental law of electrical engineering which explains the relationship between voltage and the current flowing through any resistor.

Ohm's Experiment

Ohm's law is the experimentally verified law. George Simon Ohm himself was a German scientist. To understand the law, let's look into this experiment.

Consider a variable voltage source of 0-10 V which connects with a resistor of 1 kΩ.
While applying 1 V input it is observed that the current flowing through the circuit is 1 mA. For 2 V it is 2 mA and so on. For all values of 1 V - 10 V the recorded current values are:
After going through these observations the final statement was proposed.
V ∝ I

Other forms and Formulas for Ohm's law

There are 12 different formulas which are derived from the law. These are usually expressed in the form of Ohm's Wheel and are shown below:

Practice Examples

Given below are a few examples of the law. Practice them for learning the law:

Results from our observations:
  1. For a constant input voltage, the amount of current flowing through circuit changes with the change of resistance. Current increases by decreasing the resistance and vice versa. Thus we can say that a resistor is a current controlling element.
  2. The higher the input voltage, the higher is the current flow through the resistor. Remember that over current flow can result in burning out of resistor, so never increase the input voltage beyond certain limits.


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