Faraday’s Law


In the area of ​​physics, Faraday’s law allows the macroscopic phenomena of electromagnetic induction to be established. This law investigates the study of magnetic fields, electromagnetism and electrochemistry. Based on the works of Michael Faraday in 1831 , it is a law of moderation, which means that it describes effects that are opposed to their causes. Thanks to it, a set of laws is proposed capable of quantifying the amount of energy found in the electrodes through their separation by means of electricity. Faraday’s law constitutes the fundamental law of magnetic induction according to which, the electromotive force induced in a closed filiform circuit is proportional to that derived with respect to time, from the magnetic induction flux originated by this circuit.


What is Faraday’s law?

Faraday’s law refers to any variation of flow inside a closed circuit that causes an induced current that lasts for the time of the variation . The flux can vary either by variation of the magnetic field lines, or by the variation of the intensity of the field.

  • What does it consist of
  • Faraday’s first law (first law of electrolysis)
  • Faraday’s second law (second law of electrolysis)
  • History
  • Examples where Faraday’s law applies

What does it consist of

The following explains what Faraday’s first and second laws consist of.


Faraday’s first law (first law of electrolysis)

The first law of Faraday establishes a relationship between the mass of a substance released by electrolysis and the load value has passed through the electrolyte.

This law is formulated as follows: the mass of a substance that has been assigned during electrolysis, on each electrode is directly proportional to the amount of charge that has passed through the electrolyte .


detached mass = k (constant) Q = kIt

where Q is the charge in coulombs, I the intensity in amps and t the time in seconds

Faraday’s second law (second law of electrolysis)

The second Faraday law establishes dependency electrochemical equivalent weight of the substance and of atomic valence. It is formulated as follows: the electrochemical equivalent of the substance will be proportional to its atomic weight , and inversely proportional to its valence called equivalent chemical substance . With this value, Faraday’s second law can be formulated differently: the electrochemical equivalents of the substance are proportional to its own chemical equivalents .


detached mass = k (constant) atomic weight / oxidation number

Faraday’s second law, like the first, is derived directly from the nature of the ionic current in solution.


The British Michael Faraday , one of the most important scientists for humanity despite not being well known, is the one who proposes Faraday’s law . Although he only had basic studies, he was very self-taught and was interested from a very young age in the area of physics and chemistry.

Thus, he began to experiment with what he knew, arriving at indications that led him to the discovery of electromagnetic induction and later, to carry out an experiment in which he achieved electrostatic induction, giving rise to the principle known as the Faraday cage . Being interested in both the area of ​​electromagnetism and electrochemistry , he continues to carry out studies and annotations with respect to both topics, when in 1834, he began to formulate the so-called Faraday’s laws of electrolysis , which focus on calculating from quantitatively, the amounts of energy deposited on the electrodes.

Examples where Faraday’s law applies

Here are some examples of objects that make use of Faraday’s law to fulfill their function.

Electric motors

For the creation of these gadgets, the notions of Faraday’s law are applied since they can transform electrical energy into mechanical energy, offering excellent performance compared to chemical motors.

Induction glass ceramic hobs

Induction hobs used in cooking are another invention based on the principles of Faraday’s law. These plates can detect when an object is placed on its surface and shakes it in one direction and another through magnetic waves. Energy is absorbed and it is released in the form of heat.

Magnetic brakes

The operation of the magnetic brakes that can be found in the market are based on Faraday’s law. For example, when braking, a train energizes an electromagnet on board. Said electromagnet is mounted on an elongated metal rail. The currents induced in the rail generate a force and thus the rail and the train repel each other.

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