Electromagnetic Induction - Definition, Formula, Examples, FAQs

Edited By Vishal kumar | Updated on Jul 02, 2025 04:29 PM IST

What do you mean by Electromagnetic Induction?

Electromagnetic induction definition and Electromagnetic induction meaning: A fluctuating magnetic flux arises in a closed coil when a changing current is put across it. An emf is induced in the coil as a result of this flow. It generates an induced current as a result of the induced emf. Electromagnetic induction is the phenomenon of creating induced EMF or current as a result of changing flux. :-

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What do you mean by Electromagnetic Induction?
Electromagnetic induction formula-
Electromagnetic Induction Example-
Application of Electromagnetic Induction-

Electromagnetic Induction - Definition, Formula, Examples, FAQs

Michael Faraday discovered electromagnetic induction in 1831, and James Clerk Maxwell mathematically characterized it as Faraday's law of induction. Electromagnetic induction class 12 is a current generated by the generation of voltage (electromotive force) in the presence of a changing magnetic field. When a conductor is placed in a moving magnetic field (using an AC power source), or when a conductor is constantly moving in a stationary magnetic field, this occurs.

NCERT Physics Notes:

Michael Faraday built up a conducting wire as shown below, which was connected to a device that measured the voltage across the circuit. The voltage detector monitors the voltage in the circuit when a bar magnet is moved through the coiling.

Electromagnetic induction

Electrostatic induction-

Electrostatic induction is a change in the distribution of electric induction charge on a material caused by the impact of adjacent charged particles. When an object is placed in an electric induction field, electrostatic induction occurs.

Electromagnetic induction formula-

The induced voltage can be calculated using the following formula:

$\mathrm{e}=\mathrm{N}(\mathrm{d} \Phi / \mathrm{dt})$

The induced voltage is denoted by the letter e. (in volts)
The coil's number of turns is N.
t is the time, and Φ is the magnetic flux – the amount of magnetic field at a surface (in Webbers) (in seconds)

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The significance of this finding is that it demonstrates a method of producing electric inductional energy in a circuit without the use of batteries. Electromagnetic induction is used in everyday machinery such as motors, generators, and transformers.

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Faraday’s law of electromagnetic induction-

First law: When a conductor is put in a changing magnetic field, an induced EMF is produced, and if the conductor is closed, an induced current flows through it.

The magnitude of the induced EMF is equal to the rate of change of flux connections, according to the second law.

Faraday's law of electromagnetic induction, based on his experiments, states that the amount of voltage induced in a coil is proportionate to the number of turns and the changing magnetic field of the coil.

FARADAY’S LAW ELECTROMAGNETIC INDUCTION

As a result, the induced voltage is now:

e = N (dΦ/dt)

where,

The induced voltage is denoted by the letter e.
The coil's number of turns is N.
φ is a measure of magnetic flux
t is time

Related Topics,

Lenz’s law of electromagnetic induction-

When an emf induces according to Faraday's law, the polarity (direction) of that induced emf opposes the cause of its generation, according to the Lenz law of electromagnetic induction.

Lenz's law states that,

$\mathrm{E}=-\mathrm{N}(\mathrm{d} \Phi / \mathrm{dt})($ volts $)$

Eddy current-

The current swirls in such a way that it creates a magnetic field that opposes the change, according to the Lenz law of electromagnetic induction. Eddy currents waste energy because they have a tendency to oppose one another. Eddy currents convert more usable kinds of energy like kinetic energy into heat, which isn't always useful. Although the loss of usable energy is undesirable in many electromagnetic induction applications, it does have some beneficial electromagnetic induction applications.

eddy current due to magnet

Electromagnetic Induction Example-

some trains' brakes. The brakes expose the metal wheels to a magnetic field during braking, which causes eddy currents to form in the wheels. The wheels are slowed by the magnetic interaction between the applied field and the eddy currents. The impact is larger the quicker the wheels spin, thus as the train slows down, the braking force decreases, resulting in a smooth stop.
Few galvanometers with a fixed core made of nonmagnetic metallic material exist. When the coil oscillates, the core's eddy currents oppose the motion and bring the coil to a stop.
The melting of metals in an induction furnace can be used to make alloys. The eddy currents in the metals generate a high enough temperature to melt it.

EMF (electro-motive force)-

The energy per unit electric induction charge given by an energy source, such as an electric induction generator or a battery, is known as electromotive force, abbreviated E or emf. The property of any energy source capable of pushing electric induction charge around a circuit is called electromotive force.

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Application of Electromagnetic Induction-

We now have Faraday's law, which states that the amount of voltage induced in a coil is proportional to the number of turns in the coil and the rate at which the magnetic field changes.

The principle of electromagnetic induction governs the operation of an AC generator.
The principle of electromagnetic induction governs the operation of electric inductional transformers.
The electromagnetic induction is used to power the magnetic flow meter.

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Frequently Asked Questions (FAQs)

1. What are the three most important conditions for electromagnetic induction and who discovered electromagnetic induction?

A voltage is formed by passing a wire through a magnetic field, which is known as electromagnetic induction. Physicist Michael Faraday discovered electromagnetic coil induction.

Three things influence the size of the voltage:

The magnitude of the magnetic field.
The conductor's active length.
The speed with which the conductor moves through the field.

2. Define magnetic induction, and how is it measured?

Magnetic induction image outcome

When a charged particle travels, it is subjected to a force known as the magnetic field, magnetic induction, or magnetic flux intensity. The letter 'B' stands for it. The tesla is the SI unit for magnetic induction (B). One weber per metre square equals one tesla.

3. What role does magnetic induction play in our lives?

Electric induction generators and electric induction transformers are two significant devices that rely on electromagnetic induction. Both devices are essential for producing and managing the electric induction current we rely on every day. Electromagnetic induction is used in electric induction generators to convert kinetic energy to electric inductional energy.

4. What factors influence electromagnetic induction?

The amount of voltage induced magnetism is proportional to the rate of change in the magnetic field flux and the number of turns of wire exposed to the flux change (if coiled).

5. What are the four factors that influence the induced emf?

The number of turns in a coil determines the induced e.m.f.
The rate of movement of the conductor through the magnetic field.
The conductor's overall length.
The pace at which the magnetic lines of force are severed by the conductor.

6. Can electromagnetic induction occur in a stationary conductor?

Yes, electromagnetic induction can occur in a stationary conductor if the magnetic field around it is changing. This is the principle behind transformer operation, where a changing current in one coil induces a current in another stationary coil through a changing magnetic field.

7. How does a transformer work using electromagnetic induction?

A transformer works on the principle of mutual induction. It consists of two or more coils wound around a common core. When an alternating current flows through the primary coil, it creates a changing magnetic field. This changing field induces an EMF in the secondary coil. The ratio of turns in the primary and secondary coils determines whether the transformer steps up or steps down the voltage.

8. How does electromagnetic induction relate to energy conservation?

Electromagnetic induction obeys the law of conservation of energy. The electrical energy produced through induction comes from the mechanical energy used to move the conductor or change the magnetic field. This principle is crucial in understanding the operation of generators, where mechanical energy is converted into electrical energy.

9. What is eddy current?

Eddy currents are circular electric currents induced within conductors by a changing magnetic field. They flow in closed loops within the conductor's body, perpendicular to the direction of the magnetic field. Eddy currents can cause heating in the conductor and are often considered a form of energy loss in electrical devices.

10. How can eddy currents be reduced?

Eddy currents can be reduced by:

11. How does the speed of a conductor's motion affect the induced EMF?

The speed of a conductor's motion through a magnetic field directly affects the induced EMF. A faster motion results in a greater rate of change of magnetic flux, which in turn induces a larger EMF. This relationship is linear: doubling the speed will double the induced EMF, assuming all other factors remain constant.

12. What is the difference between motional EMF and transformer EMF?

Motional EMF is induced when a conductor moves through a stationary magnetic field, while transformer EMF is induced when a stationary conductor experiences a changing magnetic field. Both are forms of electromagnetic induction, but the source of the changing magnetic flux differs.

13. How does the orientation of a conductor affect electromagnetic induction?

The orientation of a conductor relative to the magnetic field lines affects the amount of induced EMF. Maximum induction occurs when the conductor is perpendicular to the field lines, as this orientation allows for the greatest rate of change in magnetic flux. When the conductor is parallel to the field lines, no EMF is induced.

14. What is the right-hand rule in electromagnetic induction?

The right-hand rule is a method used to determine the direction of induced current in a conductor. For a straight conductor moving through a magnetic field:

15. What is the difference between self-induction and mutual induction?

Self-induction occurs when a changing current in a circuit induces an EMF in the same circuit. Mutual induction occurs when a changing current in one circuit induces an EMF in a nearby circuit. Both are forms of electromagnetic induction, but self-induction involves a single circuit, while mutual induction involves interaction between two or more circuits.

16. What is Faraday's law of electromagnetic induction?

Faraday's law of electromagnetic induction states that the induced electromotive force (EMF) in a closed circuit is directly proportional to the rate of change of magnetic flux through the circuit. Mathematically, it's expressed as ε = -N(dΦ/dt), where ε is the induced EMF, N is the number of turns in the coil, and dΦ/dt is the rate of change of magnetic flux.

17. How does Lenz's law relate to electromagnetic induction?

Lenz's law is a consequence of the conservation of energy in electromagnetic induction. It states that the direction of an induced current is such that it opposes the change in magnetic flux that caused it. This law explains why the negative sign appears in Faraday's law and helps predict the direction of induced currents.

18. What is magnetic flux?

Magnetic flux is a measure of the total magnetic field passing through a given area. It's calculated by multiplying the magnetic field strength by the area it passes through and the cosine of the angle between the field and the area's normal vector. The SI unit of magnetic flux is the weber (Wb).

19. What factors affect the strength of an induced EMF?

The strength of an induced EMF depends on several factors:

20. How does electromagnetic induction relate to AC power generation?

AC power generation relies heavily on electromagnetic induction. In a typical generator, mechanical energy is used to rotate a coil within a magnetic field or to rotate magnets around a stationary coil. This relative motion between the coil and the magnetic field induces an alternating EMF in the coil, producing AC power.

21. What is electromagnetic induction?

Electromagnetic induction is the process of generating an electric current in a conductor by changing the magnetic field around it. This phenomenon occurs when a conductor is moved through a magnetic field or when the magnetic field around a stationary conductor changes. It's the fundamental principle behind the operation of generators, transformers, and many other electrical devices.

22. Who discovered electromagnetic induction?

Electromagnetic induction was discovered by Michael Faraday in 1831. He observed that a changing magnetic field could induce an electric current in a nearby conductor. This discovery laid the foundation for the development of modern electrical technology.

23. What is the significance of Faraday's experiments with induction?

Faraday's experiments with induction were groundbreaking because they:

24. How does the concept of magnetic flux relate to electromagnetic induction?

Magnetic flux is central to electromagnetic induction. Induction occurs when there's a change in magnetic flux through a conductor. This change can happen by varying the magnetic field strength, changing the area of the conductor exposed to the field, or altering the angle between the field and the conductor. The rate of change of magnetic flux directly determines the magnitude of the induced EMF.

25. What is the difference between EMF and voltage in the context of electromagnetic induction?

EMF (electromotive force) and voltage are related but distinct concepts in electromagnetic induction. EMF is the potential difference generated by the induction process itself, while voltage is the actual potential difference measured across the conductor. In an ideal circuit with no resistance, EMF and voltage would be equal. However, in real circuits, voltage is often slightly less than EMF due to internal resistance.

26. What is the Hall effect and how is it related to electromagnetic induction?

The Hall effect occurs when a magnetic field is applied perpendicular to a current-carrying conductor, creating a voltage difference across the conductor perpendicular to both the current and the magnetic field. While not directly an example of electromagnetic induction, both phenomena involve the interaction between magnetic fields and moving charges. The Hall effect is used in sensors to measure magnetic fields, which can be useful in studying electromagnetic induction.

27. What is the role of electromagnetic induction in electric motors?

While electric motors primarily use magnetic forces to create motion, electromagnetic induction plays a crucial role in their operation. As the rotor (moving part) of the motor turns, it experiences a changing magnetic field, which induces a back EMF. This back EMF opposes the applied voltage and helps regulate the motor's speed.

28. What is the significance of the negative sign in Faraday's law?

The negative sign in Faraday's law (ε = -N(dΦ/dt)) is crucial as it represents Lenz's law. It indicates that the induced EMF opposes the change in magnetic flux that caused it. This opposition is nature's way of conserving energy and explains why work must be done to maintain induced currents.

29. How does the number of turns in a coil affect the induced EMF?

The number of turns in a coil directly affects the induced EMF. According to Faraday's law, the induced EMF is proportional to the number of turns (N) in the coil. Doubling the number of turns will double the induced EMF, assuming all other factors remain constant. This principle is utilized in transformers to step up or step down voltages.

30. How does electromagnetic induction relate to Maxwell's equations?

Electromagnetic induction is described by one of Maxwell's equations, specifically Faraday's law of induction. This equation relates the induced EMF to the rate of change of magnetic flux. Maxwell's equations as a whole describe the interrelationship between electric and magnetic fields, with electromagnetic induction being a key manifestation of this relationship.

31. What is the skin effect in electromagnetic induction?

The skin effect is a phenomenon in which alternating current tends to flow near the surface of a conductor rather than through its core. This effect is due to electromagnetic induction within the conductor itself. As frequency increases, the current is increasingly confined to the "skin" of the conductor, effectively reducing its cross-sectional area and increasing resistance.

32. How does electromagnetic shielding work?

Electromagnetic shielding works by using conductive or magnetic materials to block electromagnetic fields. When an external electromagnetic field encounters the shield, it induces eddy currents in the shielding material. These eddy currents create their own magnetic field that opposes the original field, effectively canceling it out and protecting the enclosed space.

33. What is the difference between diamagnetic, paramagnetic, and ferromagnetic materials in terms of electromagnetic induction?

These materials respond differently to magnetic fields, affecting electromagnetic induction:

34. How does electromagnetic induction relate to the operation of a metal detector?

Metal detectors use electromagnetic induction to detect metal objects. They contain a coil that produces an oscillating magnetic field. When this field encounters a metallic object, it induces eddy currents in the object. These eddy currents create their own magnetic field, which is detected by the receiver coil in the metal detector, signaling the presence of metal.

35. What is magnetic hysteresis and how does it affect electromagnetic induction?

Magnetic hysteresis is the tendency of a magnetic material to retain its magnetization even after the external magnetic field is removed. In electromagnetic induction, hysteresis can affect the efficiency of devices like transformers. It causes energy loss in the form of heat and can lead to a lag between changes in the applied magnetic field and the resulting magnetic flux in the core material.

36. How does the concept of mutual inductance apply to wireless charging?

Wireless charging uses mutual inductance between two coils. The charging pad contains a primary coil that creates an alternating magnetic field. When a device with a secondary coil is placed nearby, this changing magnetic field induces an EMF in the secondary coil, charging the device's battery. The efficiency of this process depends on the mutual inductance between the two coils, which is affected by their proximity and alignment.

37. What is the relationship between electromagnetic induction and electromagnetic waves?

Electromagnetic induction and electromagnetic waves are closely related. Changing electric fields create magnetic fields, and changing magnetic fields create electric fields – this is the essence of electromagnetic induction. This interplay between electric and magnetic fields propagating through space forms the basis of electromagnetic waves. In fact, Maxwell's prediction of electromagnetic waves was based on his understanding of electromagnetic induction.

38. How does electromagnetic induction contribute to energy losses in power transmission?

In power transmission, electromagnetic induction contributes to energy losses in several ways:

39. How does the principle of electromagnetic induction apply to geological surveys?

Electromagnetic induction is used in geological surveys through methods like magnetotellurics and controlled-source electromagnetics. These techniques involve measuring the Earth's response to natural or artificially induced electromagnetic fields. The induced currents in the Earth depend on the conductivity of subsurface materials, allowing geologists to map underground structures and locate mineral deposits or groundwater.

40. What is the role of electromagnetic induction in superconductors?

Superconductors exhibit unique behavior with respect to electromagnetic induction. When a superconductor is cooled below its critical temperature in the presence of a magnetic field, it expels the magnetic flux from its interior (the Meissner effect). This is due to induced supercurrents on the surface that create an opposing magnetic field. Additionally, the phenomenon of flux pinning in type II superconductors involves the trapping of magnetic flux lines, which has applications in creating powerful electromagnets.

41. How does electromagnetic induction relate to the operation of a SQUID (Superconducting Quantum Interference Device)?

SQUIDs use a combination of superconductivity and electromagnetic induction to detect extremely weak magnetic fields. They consist of a superconducting loop with one or two Josephson junctions. Changes in external magnetic flux induce a current in the superconducting loop, which affects the quantum interference of electron pairs across the junctions. This allows SQUIDs to measure magnetic fields with incredible sensitivity, making them useful in applications ranging from brain imaging to geophysical surveys.

42. What is the significance of Faraday cages in electromagnetic induction?

Faraday cages are enclosures made of conductive material that block electromagnetic fields. They work on the principle of electromagnetic induction. When an external electromagnetic field encounters the cage, it induces currents in the conductive material. These induced currents create their own magnetic field that cancels out the external field inside the cage. Faraday cages are used for electromagnetic shielding in various applications, from microwave ovens to protecting sensitive electronic equipment.

43. How does electromagnetic induction apply to the Earth's magnetic field and space weather?

The Earth's magnetic field interacts with charged particles from the sun (solar wind) through electromagnetic induction. As these particles move through the Earth's magnetic field, they induce electric currents in the ionosphere and magnetosphere. During solar storms, rapid changes in the Earth's magnetic field can induce strong currents in long conductors like power lines and pipelines, potentially causing damage. Understanding these induction processes is crucial for predicting and mitigating the effects of space weather on technological systems.

44. What is the principle behind induction cooktops?

Induction cooktops use electromagnetic induction to heat cooking vessels directly. A high-frequency alternating current is passed through a coil beneath the cooking surface, creating a rapidly changing magnetic field. This field induces eddy currents in the base of ferromagnetic cooking vessels placed on the surface. The resistance of the vessel to these currents causes it to heat up, while the cooktop itself remains relatively cool. This method is more energy-efficient than traditional electric or gas stoves.

45. How does electromagnetic induction relate to the concept of displacement current?

Displacement current, introduced by Maxwell, is a theoretical concept that extends Ampère's law to account for changing electric fields. While not a physical current of moving charges, displacement current produces magnetic fields just as conduction currents do. This concept completes the symmetry between electric and magnetic fields in Maxwell's equations and is crucial for explaining electromagnetic wave propagation. Both displacement current and electromagnetic induction highlight the fundamental interrelationship between changing electric and magnetic fields.

46. What is the role of electromagnetic induction in particle accelerators?

Electromagnetic induction plays a crucial role in particle accelerators, particularly in circular accelerators like synchrotrons. As charged particles circulate, they pass through radio-frequency (RF) cavities. The changing electromagnetic fields in these cavities, produced by alternating currents, induce an EMF that accelerates the particles. Additionally, the principle of induction is used in the bending magnets and focusing magnets that guide and shape the particle beam.

47. How does electromagnetic induction contribute to the generation of X-rays?

Electromagnetic induction is involved in X-ray generation in several ways: