Ohm՚s Law, Discovery of Ohm՚s Law, Relation of Voltage, Current and Resistance (For CBSE, ICSE, IAS, NET, NRA 2022)

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Ohm՚s Law

  • The first, and perhaps most important, the relationship between current, voltage, and resistance is called Ohm՚s Law,
  • In 1828, George Simon Ohm, a German physicist, derived a relationship between electric current and potential difference.
  • Certain formulas in Physics are so prevalent that they become popular knowledge that you end up memorizing without trying. In the field of Modern Physics, it is

Same as in the field of current electricity, it is the Ohm՚s law about which we will be studying in this article.

Discovery of Ohm՚s Law

  • Georg Simon Ohm was born in 1787, in Erlangen, Germany and taught mathematics in local schools and performed experiments in physics in a school physics laboratory, trying to master the principles behind electromagnetism.
  • he published papers on the way circuits conducted heat in Fourier՚s studies, in 1826,
  • Ohm published Die galvanische Kette, mathematisch bearbeitet, which described the relationship between electromotive force, current, and resistance later known as Ohm՚s law in May 1827.
  • Having received muted response upon its initial release, Ohm՚s findings would catalyze new research into electricity in the coming decades. Ohm was awarded the Royal Society՚s highest award, the Copley Medal. Gradually, the term Ohm was adopted as the unit of electrical resistance in 1872.

What is Ohm՚s Law?

  • Ohm՚s Law is a formula used to calculate the relationship between voltage, current and resistance in an electrical circuit.
  • Ohm՚s Law states that the current flowing through a conductor is directly proportional to the potential difference applied across its ends, provided the temperature and other physical conditions remain unchanged. Mathematically it can be represented as,

Potential difference Current

(When the value of V increases the value of /increases simultaneously)

V = IR


  • V is Voltage in volts (V)
  • R is Resistance in ohm ()
  • I is Current in Ampere (A)

When spelled out, it means voltage , or volts , or V

Relation of Voltage, Current and Resistance

Relation of Voltage, Current and Resistance

Symbol and Unit of Current, Voltage and Resistance

Symbol and Unit of Current, Voltage and Resistance
QuantitySymbolUnit of MeasurementUnit Abbreviation
CurrentIAmpere ( “Amp” )A
VoltageE or VVoltV

How Does Ohm՚s Law Work?

  • Ohm՚s Law describes the current flow through a resistance when different electric potentials (voltage) are applied at each end of the resistance.
  • Since we can՚t see electrons, the model or an analogy of electric circuits used to help us understand circuits better is the water-pipe analogy.
  • Water flowing through pipes is a good mechanical system that is analogous to an electrical circuit.
  • Here, the voltage is analogous to water pressure, the current is the amount of water flowing through the pipe, and the resistance is the size of the pipe.
  • More water will flow through the pipe (current) when more pressure is applied (voltage) and the bigger the pipe, (lower the resistance) .

Different Applications of Ohm՚s Law

The main applications of Ohm՚s law are:

  • To determine the voltage, resistance or current of an electric circuit.
  • Ohm՚s law is used to maintain the desired voltage drop across the electronic components.
  • Ohm՚s law is also used in dc ammeter and other dc shunts to divert the current.

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.

The Ohms Law Triangle

The Ohms Law Triangle
  • If the Value of Voltage is Asked and the Values of the Current and Resistance Are Given, then to Calculate Voltage Simply Cover V at the Top.
  • So, We Are Left with the I and R or .
  • The Equation for Voltage is Current Multiplied by Resistance. Examples of How the Magic Triangle is Employed to Determine the Voltage Using Ohm՚s Law is Given below.

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