Ohm’s law


The Ohm ‘s law shows a linear relationship that exists between the voltage and current in a circuit power. The voltage drop and resistance are responsible for establishing the flow of current through the resistance.

  • Unit: Volts
  • Symbol: V
  • Formula:   V = R ㆍ I

What is Ohm’s Law?

Ohm’s law is a theory that explains how electricity behaves depending on current , voltage, and resistance . It says that the intensity in a conductor of electricity is supplied by the voltage and that it is parallel to its resistance .

  • Who Proposed Ohm’s Law
  • History
  • Goals of Ohm’s Law
  • Statement
  • Formulas
  • Units
  • Explanation of Ohm’s law
  • What is it for
  • Curiosities
  • Conclusions
  • Examples of Ohm’s Law

Who Proposed Ohm’s Law

The creator of the law was Georg Ohm , he was born on March 16, 1789, in Erlangen, Germany and died on July 6, 1854, in Munich . Ohm was a professor of mathematics at the Jesuit College in Cologne in 1817. He was a renowned German physicist who discovered the law, which bears his name, which says that the current flow in a conductor is directly proportional to the difference in voltage. and inversely proportional to resistance.


His work began to be recognized and in 1841 he was awarded the Copley Medal of the Royal Society of London and became a foreign member a year later. The ohm , the physical unit that measures electrical resistance , also got its name.


It can be said that Ohm’s law was born at the beginning of the 19th century, and that it was discovered by the mathematician and physicist Georg Simon Ohm . At that time the electric current was already known , through the inquiries of Volta Alejandro. However, Ohm wanted to delve into Volta’s research and began to experiment with the properties of electricity . He used metal parts, until he discovered Ohm’s law, in honor of his name.

It is important to mention that the law works as an excellent contribution to the electronics branch . The law was perfected by the theory of the scientist Maxwell in which he unified magnetism with electricity.

Goals of Ohm’s Law

The objectives that have Ohm’s law are the following:

  • Identify and analyze electrical phenomena .
  • Establish the differences between static electricity and electric current .
  • Understand the structure of the atom and the forces between its particles.
  • Identify electrostatic and electrodynamic phenomena .
  • Know the operation of electrical elements .
  • Recognize the elements that make up an electrical circuit .


We can say that Ohm’s law is the description of the relationship between current, voltage and resistance. The amount of constant current through a large number of materials is directly proportional to the difference in potential or voltage between the materials.


The electrical resistance R is the factor obtained using the following formula:

V = R ㆍ I

Where V is the potential difference, R is the resistance and I is the intensity of the current.

To refer to generalizations of the law or formulated by Ohm it is used : J = σE

where J is the current density at a given location in the resistive material , E is the electric field at that location, and σ (sigma) is a material-dependent parameter called conductivity .


The basic units of Ohm’s law are as follows:

  • Tension (E)
  • Intensity (I)
  • Volts (V)
  • Ampere (A)
  • Resistance (R)
  • Ohm ꭥ
  • Power (P)
  • Watt (V)

Explanation of Ohm’s law

Ohm’s Law is one of the most primordial postulates of electronics and electricity , it was postulated by the German mathematician and physicist Georg Simon Ohm, and establishes a relationship between the intensity of the current flowing through a conductor and the voltage or voltage. between its terminals, this relationship is completed by a proportionality factor called electrical resistance .

What is it for

Ohm’s law helps us to see the relationship that can be given between the most distinguished parameters such as current , voltage and resistance . It is important because regardless of whether the circuit is simple or wide, if the behavior of the electricity within it can be anticipated before connecting it. Once you have knowledge of at least two of the parameters mentioned above.


One of the curiosities of Ohm’s law is that it tells us that the current circulates in a closed circuit which is subjected to a potential difference but is proportionally applied and inversely proportional to its resistance . As the volts increase, the intensity increases.


The conclusions that we can obtain from Ohm’s law are the following:

  • The higher the voltage , the better the resistance margin of error .
  • It is noticeable that the voltage fluctuation influences the measurements that are made, which does not allow the correct taking of the values .
  • By transmitting voltage to the resistors, they become part of the heat energy .
  • The resistance is opposition to the flow of electrons .
  • The intensity is directly proportional to the voltage and inversely proportional to the resistance .

Examples of Ohm’s Law

Some examples of how to apply Ohm’s law are as follows:

Example 1: Calculate the resistance where there is a voltage of 5 V and a current of 500 mA

  • R = V / I
  • R =?
  • V = 5V
  • I = 500 mA = 0.5 A
  • R = V / I = 5 / 0.5 = 10
  • The resistance is 10 W

Example 2: Calculate the voltage in a circuit in which there is a current of 2.5 Amps with a resistance of 50 W.

  • V = RI
  • R = 50 W
  • V =?
  • I = 2.5 A
  • V = RI = (50) (2.5) = 125
  • The voltage is 125V

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