What are Faraday’s Laws of Electromagnetic Induction?

Electromagnetic induction is the generation of voltage as a result of changes in the magnetic field. To learn more about it, let’s know about Michael Faraday. 

Michael Faraday

Michael Faraday was an English scientist who made contributions to electromagnetic and electrochemistry research. The concepts underpinning electromagnetic induction, diamagnetism, and electrolysis are among his most important discoveries. 

Besides having minimal formal schooling, Faraday was one of the most outstanding scientists in history. Faraday introduced the notion of the electromagnetic field in physics through his studies on the magnetic field surrounding a conductor carrying a direct current. Faraday also demonstrated that magnetism could impact light beams and that there was a link between the two phenomena. 

What are Faraday’s Laws?

The fundamental rule of electromagnetism predicts how a magnetic field would interact with an electric circuit to create an electromotive force (EMF). This is alluded to as electromagnetic induction. 

What are Faraday’s Laws of Electromagnetic Induction?

In 1831, Michael Faraday proposed the rules of electromagnetic induction. Faraday’s law is the consequence of Faraday’s experiments. To uncover the phenomena of electromagnetic induction, he conducted three major experiments. Let’s see what those are. 

The First Law of Faraday

The first law of Faraday’s Electromagnetic Induction states that an electromagnetic field is created when a wire is held in a field with a continual change in its magnetic field. This process of electromagnetic field formation is known as an induced emf. A current is induced within the circuit if it is a closed circuit. “Induced Current” is the technical term for it. 

Here are several methods for varying the magnetic field strength in a closed loop: 

  • By rotating the coil with respect to the magnet attraction. 
  • By altering or adjusting the coil’s position in the magnetic field. 
  • By varying the area of a coil in a magnetic field. 
  • By pushing a magnet closer or further away from the coil. 

The Second Law of Faraday

Let us now examine Faraday’s second law. Another Faraday rule on Electromagnetic Induction. According to the law, the induced emf in a conductor is equal to the rate at which the flux is linked to the circuit changes. In this case, the flux is the product of the flux in the wire and the number of turns in the wire. 

The formula for Faraday’s Law

Let us look at how Faraday’s Law came to be. Let us first define certain terms: 

Where, 

\(\epsilon\) = the emf or electromotive force 

\(\phi\) = the magnetic flux 

N = the total number of turns in the coil 

The quantity of electromotive force (ε) created in the circuit is equal to the rate at which the magnetic flux varies through the circuit. The preceding statement or equation can be written as follows: 

\( \epsilon = \frac{dt}{d \phi }\)

The difference in potential created throughout an “unloaded loop” is the electromotive force or EMF. This occurs when the resistance in the circuit reaches a critical level. Because EMF and voltage are both measured in voltage, EMF may also be thought of as voltage. 

Faraday’s Law is not the only relevant law that defines the electromotive force. 

Heinrich Lenz proposed Lenz’s law in 1833. Whereas Faraday’s Law defines the quantity of EMF created within the circuit, Lenz’s Law indicates the direction of current flow inside the circuit. According to the rule, the direction of the current will be opposite to the direction of the flux that created it. In other words, the direction of any magnetic field created by the “induced current” is the inverse of the direction of the real field modification. 

Lenz’s Law and Faraday’s Law both reach the same result. The sole distinction is the (minus “-“). This negative sign indicates that the magnetic field direction and the induced emf direction are opposing. 

\( \epsilon = – \frac{dt}{d \varphi }\)

If the coil has N turns, then the total magnetic induction in the coil is given as

\( \epsilon = -N \frac{dt}{d \phi }\)

Faraday’s Experiment

Relationship Between Induced EMF and Flux:

The first Faraday’s Law stated that when the overall intensity of the magnetic field changes, only a current is induced in the circuit. This was demonstrated by attaching an ammeter to the wire loop. This ammeter is deflected when the magnet moves in the direction of the wire. 

Faraday’s second experiment indicated that when current travels through an iron rod, it becomes electromagnetic. He also discovered that the relative motion of the coil and the magnet produces an induced electromagnetic force. 

  • When the magnet revolves around its axis, no EMF is created; however, when the magnet rotates on its axis, induced EMF is produced. When the magnet is motionless or set in its place, there is no deflection in the ammeter. 
  • When the magnet moved close to the coil, the voltage measured increased to its maximum. 
  • The amount of voltage created as the magnet goes away from the wire is in the opposite direction of the loop. 

The third experiment was carried out and documented. When the coil was stationary in this experiment, there was no deflection in the galvanometer. The induced current was therefore created in the coil. However, as the magnet moved away from the circuit, the ammeter deflected away from the loop. 

Application of Faraday’s Laws

  • Faraday’s Law governs the operation of transformers and other electrical equipment.  
  • The induction cooker works on the idea of reciprocal induction, which is based on Faraday’s Law. 
  • Inducing an EMF into electromagnetic flowmeter aid in the recording of liquid flow speed. 
  • Faraday’s Laws are also used in numerous medical technologies, including MRI scanners, X-ray machines, and CT scanners. 

Conclusion

After doing the above tests, Faraday concluded that if there is relative motion between a wire and a magnetic field, the total amount of flux linkage in the coil varies. This flux shift causes a voltage to be generated in the coil. The law also indicates that the EMF or electromotive force is created as the magnetic flux changes over time. Stay connected to Tutoroot for more interesting articles like this. Register for a plethora of interactive, interesting Physics-related courses as well as limitless personalized assistance. 

FAQ’s

What is Lenz’s Law? 

Lenz’s law, “the polarity of induced emf tends to create a current that opposes the change in magnetic flux that caused it.” 

What is Flux? 

Flux is the number of electric or magnetic field lines that travel across a surface in a particular length of time. 

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