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Electromagnetism - Definition, Force, Properties, Applications, FAQs

Electromagnetism - Definition, Force, Properties, Applications, FAQs

Edited By Vishal kumar | Updated on Jul 02, 2025 04:43 PM IST

Electromagnetism is an underlying concept in physics that deals with the interaction between an electric field and a magnetic field. It lays the foundation for modern technology. In this article, we will review what is electromagnetic force, what is an electromagnet and its applications, electromagnetic force examples, and properties, electromagnetic effect, electromagnetic field, electrodynamics, some laws related to electromagnetism and magnetism and electromagnetism.

This Story also Contains
  1. Define Electromagnetism
  2. What is Electromagnetic Force
  3. What is an Electromagnet
  4. Key Components of Electromagnetism
  5. Bio-Savart Law
  6. Ampere's Circuital Law
  7. Faraday's Law of Electromagnetism
  8. Magnetism and Electromagnetism
Electromagnetism - Definition, Force, Properties, Applications, FAQs
Electromagnetism - Definition, Force, Properties, Applications, FAQs

Define Electromagnetism

Electromagnetism is a field of physics that focuses on the study of electric fields and magnetic fields and the interaction between them. The electromagnetic force is a manner of physical contact that exists between electrically charged particles. When a conductor crosses the lines of force in a magnetic field, Michael Faraday discovered that an electric current can be generated. With his famous kite-flying experiments in 1752, Benjamin Franklin discovered electricity.

Electromagnetic fields, which are made up of electric and magnetic fields, contain the electromagnetic force, which is responsible for electromagnetic radiation like light. Together with the strong interaction, the weak interaction, and gravitation, it is one of the four fundamental interactions in nature that are often referred to as forces.

Electromagnetism is widely used in modern technology, and electromagnetic theory serves as the foundation for electrical power, engineering, and electronics, including digital technology. The electromagnetic field can be described mathematically in a variety of ways.

What is Electromagnetic Force

Electromagnetic force definition: The force between charged particles is known as the electromagnetic force. At rest, unlike charges are attracted to each other, whereas similar charges repel each other. Magnetic force is created by moving charges. Electromagnetic Force is the name given to these forces when they are combined. All chemical processes that originate from interactions between electrons of nearby atoms are governed by electromagnetic force.

Electromagnetic Force Formula:

$$
\vec{F}=q(\vec{E}+\vec{v} \times \vec{B})
$$

where,

  • $\vec{F}$ is the electromagnetic force
  • $q$ is the charge of the particle
  • $\vec{E}$ is the electric field
  • $\vec{v}$ is the velocity of the particle
  • $\vec{B}$ is the magnetic field
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The electromagnetic force, also characterized as the Lorentz force, is used to define electromagnetic phenomena, which incorporates both electricity and magnetism as distinct manifestations of the same phenomenon. The electromagnetic force is a major factor in defining the interior properties of most everyday items. Except for gravity, the electromagnetic force is responsible for virtually all phenomena encountered in daily life. The movement of these particles carries momentum, which is explained by electromagnetic forces.

Properties of Electromagnetic Force

The electromagnetic force has the following properties:

  • It obeys the concept of inverse squares.
  • The photon is an electromagnetic force field particle.
  • It has the potential to be both seductive and repellent.
  • It is both a central and a conservative force.
  • It is a force with a long range.
  • It has a strength of around 1036 times that of gravity.

Electromagnetic Force Examples

  1. Electric motors
  2. Generators and Transformers
  3. Electromagnets
  4. Induction cooking
  5. Magnetic attraction and repulsion

What is an Electromagnet

Electromagnet definition: An electromagnet is a magnet whose magnetic field is supplied by an electric current. Wire looped into a coil is used to build electromagnets. The flow of electric current generates a magnetic field that is concentrated in the hole, which functions as the coil's center. When the current is completely off, the magnetic field fades.

An electromagnet is a device that creates electricity to generate a magnetic field. The electromagnet was discovered in 1825 by British electrical engineer William Sturgeon, a former soldier who began dabbling in the sciences at the age of 37.

Applications of Electromagnets

Television

In television, electromagnetism is quite significant. Electromagnets produce the electron beam, which scans the image area. Similarly to how a monochromatic tube scans the screen in a television, the electromagnetic deflection brace deflects or bends the beams.

Speaker

Electrical energy is converted into mechanical energy by speakers (motion). Mechanical energy compresses air and transforms motion into sound energy or sound pressure level (SPL). A magnetic field is generated when an electric current is passed through a coil of wire.

An electromagnet is put in front of a permanent magnet inside the speaker. An electromagnet is moveable, whereas the permanent magnet is set in place. The direction of the electromagnet's magnetic field is rapidly modified when pulses of electricity run through its coil. This means it is attracted to and repulsed by the permanent magnet, which vibrates back and forth. The electromagnet is connected to a flexible cone composed of paper or plastic, which amplifies the vibrations and pumps sound waves into the surrounding air toward our ears.

Magnetic levitation trains

Magnetic levitation is a technique for suspending an object using just magnetic fields as a support. Two sets of magnets are used in magnetic levitation trains, one to repel and push the vehicle off the track, and the other to propel the floating train forward at high speeds without friction. There are no moving parts in this technique. The train moves along a magnetic guideway that uses basic magnet principles to control the train's stability and speed.

Medical system:

Electromagnetic fields are being used in modern medical devices such as cancer hyperthermia treatments, implants, and magnetic resonance imaging (MRI). Electromagnetism-based sophisticated technology can scan even minute aspects of the human body.

Key Components of Electromagnetism

Electromagnetic Field

Accelerating electric charges creates a classical electromagnetic field, which is the classical equivalent to the quantized electromagnetic field tensor in quantum electrodynamics and is described by classical electrodynamics. The fundamental SI unit is the ampere, which is part of a system of electrical units based mostly on the magnetic characteristics of electric currents.

Electromagnetic Effect

The influence of electric and magnetic fields on diverse materials is known as the electromagnetic effect. Water, for illustration, is dipolar but partially aligned when it comes into contact with an electric field and is diamagnetic.

Electrodynamics

The branch of physics is concerned with the effects of electric currents interacting with magnets, with other currents, or with themselves.

Principles of Electromagnetics

The electromotive force induced in the loop due to changing magnetic flux is equal to the rate of change of the magnetic flux threading loop, as per Faraday's Principle of Electromagnetic Induction. Moving a bar magnet in and out of a coil of wire can modify the magnetic flux threading it.

Bio-Savart Law

The Bio-Savart law states that the magnetic field produced by the current element at a given point is directly proportional to the current, the length of the segment, and the sine of the angle between the line element and the one that connects the line to the point.

$$
d \vec{B}=\frac{\mu_0}{4 \pi} \frac{I d \vec{l} \times \vec{r}}{r^3}
$$

where,

  • $d \vec{B}$ is the magnetic field produced by the current element
  • $\mu_0$ is the permeability of free space
  • $I$ is the current flowing through the conductor
  • $d \vec{l}$ is the length of the current element
  • $\vec{r}$ is the position vector
  • $r$ is the magnitude of $\vec{r}$.

Ampere's Circuital Law

Ampere's circuital law states that the line integral of the magnetic field around a closed loop is directionally proportional to the total current passing through the closed loop.

$$
\oint_{\mathcal{C}} \vec{B} \cdot d \vec{l}=\mu_0 I_{\mathrm{enc}}
$$

where,

  • $\oint_{\mathcal{C}} \vec{B} \cdot d \vec{l}$ is the the line integral of the magnetic field
  • $\mu_0$ is the permeability of free space
  • $I_{\text {enc }}$ is the total current enclosed by the path

Faraday's Law of Electromagnetism

Faraday's law states that the induced EMF in a closed loop is directly proportional to the rate of change of magnetic flux passing through the close.d loop

$$
\mathcal{E}=-\frac{d \Phi_B}{d t}
$$

where,

  • $\mathcal{E}$ is the induced EMF
  • $\Phi_B$ is the magnetic flux through the loop
  • $\frac{d \Phi_B}{d t}$ is the rate of change of magnetic flux

Magnetism and Electromagnetism

Electromagnetism is the science of charge and the forces and fields that accompany it. Electromagnetism encompasses the following: electricity and magnetism. For a long time, electricity and magnetism were considered to be two different forces.

Subparts of Magnetism

Magnetic Force

The attraction or repulsion that emerges between electrically charged particles as a result of their motion is known as magnetic force. It is the fundamental force that causes effects like the activity of electric motors and the attraction of magnets to iron.

Electromagnetic Repulsion Force

The electromagnetic force, like gravity, is an infinite-range attracting force that influences everything in the cosmos. It is also a repulsive force that acts between charged particles.

NCERT Physics Notes:

Frequently Asked Questions (FAQs)

1. Define Electromagnetism.

The electromagnetic force, a manner of physical contact that exists between electrically charged particles, is analysed in electromagnetism, a part of physics. The force F experienced by a conductor of length L kept perpendicular to the magnetic field B is given by the equation F=ILB if a current I is flowing through it.

2. What is Electromagnetic force?

The force between charged particles is known as the electromagnetic force. At rest, unlike charges are attracted to each other, whereas similar charges repel each other. Magnetic force is created by moving charges. Electromagnetic Force is the name given to these forces when they are combined. The electromagnetic force, also characterized as the Lorentz force.

3. What are the properties of the electromagnetic force?

The electromagnetic force has the following properties:

  • It obeys the concept of inverse squares.

  • The photon is an electromagnetic force field particle.

  • It has the potential to be both seductive and repellent in nature.

  • It is both a central and a conservative force.

  • It is a force with a long range.

  • It has a strength of around 1036 times that of gravity.

4. Define Electromagnetic effect.

The influence of electric and magnetic fields on diverse materials is known as the electromagnetic effect. Water, for illustration, is dipolar in nature but partially aligned when it comes into contact with an electric field and is diamagnetic.

5. Who discovered electromagnets and electromagnetism?
  • An electromagnet is a device that creates electricity to generate a magnetic field. The electromagnet was discovered in 1825 by British electrical engineer William Sturgeon, a former soldier who began dabbling in the sciences at the age of 37.

  • When a conductor crosses the lines of force in a magnetic field, Michael Faraday discovered that an electric current can be generated.

6. What is the significance of Faraday's experiments with induction?
Faraday's experiments with induction were groundbreaking as they demonstrated that electricity and magnetism were interconnected phenomena. His work laid the foundation for the development of electric motors, generators, and transformers, which are crucial to modern technology and power distribution systems.
7. How does electromagnetic induction relate to Faraday's concept of field lines?
Faraday introduced the concept of field lines to visualize magnetic fields. In electromagnetic induction, the induced EMF is proportional to the rate at which a conductor cuts across these field lines. This visualization helps in understanding why the orientation of a conductor in a magnetic field affects the induced current.
8. What is the significance of the minus sign in Faraday's law equation?
The minus sign in Faraday's law equation (ε = -dΦ/dt) represents Lenz's law. It indicates that the induced EMF opposes the change in magnetic flux that causes it. This opposition is crucial for understanding the behavior of induced currents and their effects on the system.
9. How does the orientation of a coil affect the induced EMF in electromagnetic induction?
The orientation of a coil relative to the magnetic field affects the induced EMF. Maximum EMF is induced when the coil is perpendicular to the field lines (maximum flux change), while no EMF is induced when the coil is parallel to the field lines (no flux change). This principle is used in AC generators to produce sinusoidal voltage.
10. What factors affect the magnitude of the induced EMF in electromagnetic induction?
The magnitude of the induced EMF depends on several factors: the strength of the magnetic field, the rate of change of the magnetic field or the motion of the conductor, the number of turns in the coil (if applicable), and the area of the loop or coil. Increasing any of these factors will generally increase the induced EMF.
11. How does electromagnetic induction contribute to the generation of eddy current brakes?
Eddy current brakes use electromagnetic induction to create a braking force. When a conductive material moves through a magnetic field, eddy currents are induced in the material. These currents create their own magnetic fields that oppose the motion, resulting in a braking effect. This principle is used in some trains and roller coasters for smooth, wear-free braking.
12. What is the relationship between electromagnetic induction and Maxwell's equations?
Electromagnetic induction is described by Faraday's law, which is one of Maxwell's four equations. These equations collectively describe how electric and magnetic fields are generated and interact. Faraday's law specifically relates the induced EMF to the changing magnetic flux, forming a crucial part of the unified theory of electromagnetism.
13. What is the significance of the mutual inductance coefficient in electromagnetic induction?
The mutual inductance coefficient (M) quantifies how effectively the changing current in one circuit induces an EMF in another circuit. It depends on the geometry of the circuits and their relative positions. A higher mutual inductance means a stronger coupling between the circuits, which is crucial in designing efficient transformers.
14. What is the skin effect in conductors, and how is it related to electromagnetic induction?
The skin effect is the tendency of alternating current to flow near the surface of a conductor. It's a consequence of electromagnetic induction within the conductor itself. Eddy currents induced by the changing magnetic field inside the conductor cause the current density to be highest near the surface, effectively increasing the resistance for high-frequency currents.
15. How does electromagnetic induction relate to the concept of magnetic vector potential?
The magnetic vector potential (A) is a mathematical tool used to describe magnetic fields. In electromagnetic induction, changes in the magnetic vector potential can induce an electric field, even in regions where the magnetic field itself is zero. This concept is particularly useful in understanding phenomena like the Aharonov-Bohm effect.
16. What is the difference between electromagnetic induction and electromagnetic radiation?
While both phenomena involve changing electromagnetic fields, electromagnetic induction specifically refers to the generation of electric current in a conductor due to a changing magnetic field. Electromagnetic radiation, on the other hand, involves the propagation of energy through space in the form of coupled electric and magnetic fields, not requiring a conductor.
17. What is the role of electromagnetic induction in the generation of eddy currents in the Earth's core?
Electromagnetic induction plays a crucial role in generating eddy currents within the Earth's liquid outer core. The motion of the conductive molten iron in the presence of the Earth's magnetic field induces these currents. These induced currents, in turn, generate magnetic fields, contributing to the self-sustaining geodynamo that maintains the Earth's magnetic field.
18. How does Faraday's law of induction relate to electromagnetic induction?
Faraday's law of 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. This law quantifies the relationship between the changing magnetic field and the induced current, forming the foundation of electromagnetic induction.
19. 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 was discovered by Michael Faraday and forms the basis for many modern technologies, including electric generators and transformers.
20. What is magnetic flux, and why is it important in electromagnetic induction?
Magnetic flux is a measure of the total magnetic field passing through a given area. It's crucial in electromagnetic induction because changes in magnetic flux are what induce an electromotive force (EMF) in a conductor. The greater the rate of change of magnetic flux, the larger the induced EMF.
21. Can electromagnetic induction occur without motion?
Yes, electromagnetic induction can occur without physical motion. While moving a conductor through a magnetic field is one way to induce current, changing the strength of a stationary magnetic field near a conductor can also induce current. This principle is used in transformers, where the changing current in one coil induces current in another without any moving parts.
22. How do eddy currents relate to electromagnetic induction?
Eddy currents are circular electric currents induced within conductors by a changing magnetic field. They are a consequence of electromagnetic induction and can cause heating in the conductor. While sometimes undesirable, eddy currents are also used in applications like induction heating and electromagnetic braking.
23. How does an electric generator convert mechanical energy into electrical energy?
An electric generator uses electromagnetic induction to convert mechanical energy into electrical energy. It typically consists of a coil of wire rotating in a magnetic field. As the coil rotates, it cuts through the magnetic field lines, inducing an alternating current in the coil. The mechanical energy driving the rotation is thus converted into electrical energy.
24. How does the concept of magnetic flux relate to the area of a loop in electromagnetic induction?
Magnetic flux is the product of the magnetic field strength, the area of the loop, and the cosine of the angle between the field and the normal to the loop's plane. Changing the area of the loop (for instance, by rotating it in a magnetic field) can change the magnetic flux, thereby inducing an EMF.
25. What is back EMF, and why is it important in electric motors?
Back EMF (electromotive force) is the induced voltage in an electric motor that opposes the applied voltage. It's a result of the motor's own rotation, which induces an EMF according to Faraday's law. Back EMF is important because it limits the current in the motor, preventing overheating and allowing the motor to run efficiently.
26. What is the role of electromagnetic induction in wireless charging technologies?
Wireless charging uses electromagnetic induction to transfer energy between two objects through electromagnetic fields. A changing magnetic field in the charging pad induces a current in a coil within the device being charged, similar to how a transformer works. This allows for convenient charging without direct electrical contacts.
27. How does electromagnetic induction contribute to the functioning 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 currents create their own magnetic field, which is detected by the device, indicating the presence of metal.
28. How does electromagnetic induction differ from electrostatic induction?
Electromagnetic induction involves the generation of an electric current in a conductor due to a changing magnetic field. Electrostatic induction, on the other hand, involves the redistribution of electric charges in an object due to the influence of a nearby charged object, without any current flow.
29. What is Lenz's law, and how does it relate to electromagnetic induction?
Lenz's law states that the direction of an induced current is such that it opposes the change that caused it. This law explains why, for example, dropping a magnet through a copper tube is slowed by the induced currents. Lenz's law is a consequence of the conservation of energy and helps predict the direction of induced currents.
30. 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, on the other hand, occurs when a changing current in one circuit induces an EMF in a nearby circuit. Transformers operate on the principle of mutual induction between two coils.
31. How does a transformer work using electromagnetic induction?
A transformer uses electromagnetic induction to transfer electrical energy between two circuits. It consists of two coils wound around a common iron core. When an alternating current flows through the primary coil, it creates a changing magnetic field. This changing field induces a voltage in the secondary coil. The ratio of turns in the coils determines whether the voltage is stepped up or down.
32. What is the right-hand rule in electromagnetic induction, and how is it used?
The right-hand rule is a method to determine the direction of the induced current in a conductor moving through a magnetic field. Point your thumb in the direction of the conductor's motion, your index finger in the direction of the magnetic field, and your middle finger (perpendicular to both) will then point in the direction of the induced current.
33. How does electromagnetic induction contribute to the generation of electromagnetic waves?
Electromagnetic induction plays a crucial role in the generation of electromagnetic waves. Accelerating charges create changing electric fields, which in turn induce changing magnetic fields. This continuous interplay between electric and magnetic fields, propagating through space, forms electromagnetic waves, as described by Maxwell's equations.
34. How does the concept of electromagnetic induction apply to the Earth's magnetic field and electric currents in the ionosphere?
The Earth's rotating magnetic field induces electric currents in the ionosphere through electromagnetic induction. These currents, in turn, create their own magnetic fields, contributing to the complex magnetosphere of Earth. This interaction plays a role in various atmospheric phenomena and affects radio wave propagation.
35. 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 in a stationary conductor by a changing magnetic field. Both are forms of electromagnetic induction, but the source of the changing magnetic flux differs.
36. How does electromagnetic induction relate to the conservation of energy?
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 and the concept of back EMF in motors.
37. What is the significance of the induced electric field in electromagnetic induction?
The induced electric field is a non-conservative field created by a changing magnetic field, as described by Faraday's law. Unlike electrostatic fields, this induced field can exist in empty space and is responsible for driving currents in conductors. Understanding this concept is crucial for grasping the nature of electromagnetic waves and induction phenomena.
38. What is the role of electromagnetic induction in the functioning of guitar pickups?
Guitar pickups use electromagnetic induction to convert string vibrations into electrical signals. The pickup consists of a magnet wrapped with a coil of wire. When a metal string vibrates near the pickup, it disturbs the magnetic field, inducing a small current in the coil. This current is then amplified to produce the guitar's sound.
39. How does the concept of electromagnetic induction apply to the functioning of induction cooktops?
Induction cooktops use electromagnetic induction to heat cooking vessels directly. A high-frequency alternating current in a coil beneath the cooktop surface creates a rapidly changing magnetic field. This field induces eddy currents in the base of magnetic cookware, generating heat through resistive heating, while the cooktop itself remains cool.
40. How does the concept of electromagnetic induction apply to the detection of seismic waves?
Electromagnetic induction is used in some seismometers to detect ground motion. A magnet moves relative to a coil during seismic activity, inducing a current in the coil. The magnitude and frequency of this induced current provide information about the seismic waves, allowing for the measurement of earthquake intensity and characteristics.
41. How does the principle of electromagnetic induction apply to the functioning of RFID (Radio-Frequency Identification) technology?
RFID technology uses electromagnetic induction for short-range communication. The RFID reader creates an oscillating magnetic field, which induces a current in the antenna of the RFID tag when it's nearby. This induced current powers the tag's chip, allowing it to transmit information back to the reader through modulated electromagnetic waves.
42. What is the significance of Faraday cages in relation to electromagnetic induction?
Faraday cages are enclosures made of conductive material that block external electric fields. They work on the principle of electromagnetic induction. When an external electric field is applied, it induces charges on the cage's surface, creating an opposing field inside the cage that cancels the external field. This protects sensitive equipment from electromagnetic interference.
43. How does electromagnetic induction contribute to the phenomenon of magnetic levitation?
In some magnetic levitation systems, electromagnetic induction plays a key role. When a conductive object moves through a magnetic field, eddy currents are induced in the object. These currents create their own magnetic field that opposes the original field, resulting in a repulsive force. This principle is used in some maglev train designs for levitation and propulsion.
44. What is the relationship between electromagnetic induction and the Hall effect?
While both phenomena involve the interaction of charged particles with magnetic fields, they differ in their mechanisms. Electromagnetic induction involves generating current through changing magnetic fields, while the Hall effect involves the deflection of moving charges in a conductor due to a magnetic field. However, both effects are important in understanding the behavior of charged particles in electromagnetic fields.
45. How does the principle of electromagnetic induction apply to the detection of metal objects in security scanners?
Security scanners often use electromagnetic induction to detect metal objects. The scanner creates an oscillating magnetic field. When a metal object passes through this field, eddy currents are induced in the object. These currents create a secondary magnetic field that is detected by the scanner, alerting security personnel to the presence of metal items.
46. What is the role of electromagnetic induction in the generation of alternating current?
Electromagnetic induction is fundamental to the generation of alternating current (AC). In AC generators, a coil is rotated in a magnetic field, or vice versa. This continuous change in the magnetic flux through the coil induces an alternating EMF, resulting in an alternating current. This principle is the basis for most of the world's electrical power generation.
47. How does electromagnetic induction contribute to the functioning of electric guitars and other electric instruments?
Electric guitars and similar instruments use electromagnetic induction in their pickups. These pickups consist of magnets wrapped with wire coils. When a metal string vibrates, it disturbs the magnetic field around the pickup, inducing a small current in the coil. This induced current is then amplified to produce the instrument's sound, effectively converting mechanical vibrations into electrical signals.
48. What is the significance of electromagnetic induction in the field of plasma physics?
In plasma physics, electromagnetic induction plays a crucial role in various phenomena and applications. For instance, in tokamaks (devices used in fusion research), changing magnetic fields are used to induce currents in the plasma, heating it and confining it within the reactor. Understanding induction is also vital for studying astrophysical plasmas and their interactions with magnetic fields.
49. How does the concept of electromagnetic induction apply to the functioning of electromagnetic flow meters?
Electromagnetic flow meters use Faraday's law of induction to measure the flow rate of conductive liquids. As the liquid flows through a pipe, it passes through a magnetic field created by the meter. This motion induces a voltage perpendicular to the flow and the magnetic field. The magnitude of this induced voltage is proportional to the flow rate, allowing for accurate measurement.
50. What is the relationship between electromagnetic induction and the concept of magnetic reconnection in space physics?
While electromagnetic induction and magnetic reconnection are distinct phenomena, they both involve changing magnetic fields. Magnetic reconnection occurs when magnetic field lines break and reconnect, releasing energy. This process can induce electric fields and currents in surrounding plasma, similar to electromagnetic

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