Copyright

Electromagnetic Induction

Shikha Chellaiyan, Jim Heald, Christianlly Cena
  • Author
    Shikha Chellaiyan

    Shikha has a master’s degree in Instructional Design and Technology. She has an experience of over ten years in writing instructional learning content.

  • Instructor
    Jim Heald

    Jim has taught undergraduate engineering courses and has a master's degree in mechanical engineering.

  • Expert Contributor
    Christianlly Cena

    Christianlly has taught college physics and facilitated laboratory courses. He has a master's degree in Physics and is pursuing his doctorate study.

See the electromagnetic induction definition and examples. Learn about Faraday's Law, induced electrical fields and how electromagnetic induction occurs. Updated: 08/10/2021

Table of Contents

Show

Electromagnetic Induction: Definition and Introduction

Did you know that in the earlier centuries, electricity and magnetism were thought to be unrelated? It was only through various scientific experiments it was established that a moving electric current could produce a magnetic field. The discovery helped produce electricity on large scales as it led to the development of transformers and generators.

What is Electromagnetic Induction?

In electromagnetic induction, a current is produced in a wire due to a change in the magnetic field.

Electromagnetic induction phenomena can be explained by a simple example of a coil and a magnet. When a magnet is brought towards a coil, a relative motion is generated between the two due to a magnetic flux. This leads to an electromotive force which results in an electric current in the coil. The flow of the current can be checked with the galvanometer.

The direction of motion changes when a bar magnet is pushed towards the coil.

The direction of motion changes when a bar magnet is pushed towards the coil.

History

In 1831 Michael Faraday discovered electromagnetic induction in one of his experiments. Joseph Henry also did independent research on electromagnetic induction. A series of experiments conducted by Faraday and Henry led to understanding electromagnetic induction and its benefits. Let's look at these experiments in detail.

An error occurred trying to load this video.

Try refreshing the page, or contact customer support.

Coming up next: Electromagnetic Induction: Conductor to Conductor & Transformers

You're on a roll. Keep up the good work!

Take Quiz Watch Next Lesson
 Replay
Your next lesson will play in 10 seconds
  • 0:05 Electromagnetic Induction
  • 3:10 Applications of…
  • 6:03 Lesson Summary
Save Save Save

Want to watch this again later?

Log in or sign up to add this lesson to a Custom Course.

Log in or Sign up

Timeline
Autoplay
Autoplay
Speed Speed

How Does Electromagnetic Induction Occur?

Experiment 1

In this experiment, a coil is connected to the galvanometer. When the North-pole of the bar magnet is brought towards the coil, the galvanometer deflects. This indicates the presence of an electric current in the coil. If the magnet moves, the deflection lasts.

A reversal of electric current occurs when the magnet is taken aback since the galvanometer deflection is in the opposite direction.

Similarly, when the South-pole is moved towards the coil, the deflections are in the opposite direction.

This experiment shows how electromagnetic induction occurs, i.e., that an electric current is induced due to the relative motion between the coil and the magnet.

The direction of motion changes when a bar magnet is pushed towards the coil.

The direction of motion changes when a bar magnet is pushed towards the coil.

Experiment 2

In the second experiment, Faraday took another coil instead of the bar magnet. An electric current is induced there when a current is passed through the primary coil and is moved towards the secondary coil. Similarly, if the first coil is moved in the opposite direction, the deflection in the galvanometer is in the opposite direction.

This experiment shows how an electric current is induced due to a relative motion between two coils.

Experiment 3

In this experiment, two electronic coils are retaken; one is connected to a galvanometer, and another is connected to the battery through a tapping key. If the tapping is pressed, the galvanometer shows temporary deflection. If the tapping key is pressed continuously, there is no deflection. When the key is released, a deflection occurs in the opposite direction.

This experiment shows that a relative motion is not necessary to induce an electric current.

Current is induced in the secondary coil due to the current in the primary coil with a tapping key.

Current is induced in the secondary coil due to the current in the primary coil with a tapping key.

What is Magnetic Flux?

Faraday's experiments helped derive a simple mathematical formula for magnetic flux. Magnetic flux can be defined as the total magnetic field through a given area.

Φ = BA cosθ

If we choose a simple flat surface with area A as our test area, then:

θ—Angle

Magnitude B — Magnetic field vector

Magnetic Flux

Faraday's Law

Faraday's law of induction states that the magnitude of induced electromagnetic force (emf) in a circuit is equal to the time rate of change of magnetic flux through the circuit. The relationship is:

Emf = - ΔΦ /Δt

Where Φ —BA—magnetic flux

B—external magnetic field

A— area of the coil

T—time

(-)— The negative sign indicates the direction of current in the closed-loop

When this closely wound coil turns N turns, the flux change with each turn is also the same.

Emf = - NΔΦ /Δt

Where N— Number of turns

Lenz's Law

As per Lenz's Law, an induced electromotive force produces a current in the loop that opposes the change in magnetic flux that produces it. Lenz's law is based base on the principle of energy conservation.

Emf = -NΔΦ/ Δt

The direction of the induced current is opposite to the change producing it.

The direction of the induced current is opposite to the change producing it.

Electromagnetic Induction Examples and Applications

In modern society, Faraday's law of induction sees several applications.

  • One example is data storage which is done by recording with the help of magnetic fields. In some computers, hard drives data is recorded on a spinning disk that is coated.
  • Tablets used by many graphic artists use the same principle. A battery-operated pen is used on a screen that is connected by several wires. The magnetism coming from the tip induces the emf on the screen, translating into graphical images that the artist draws.
  • Hybrid or electric vehicles also work on the principle of electromagnetic induction. It also sees an application in treating patients with mental disorders like hallucinations and depression by way of transcranial magnetic stimulation (TMS). Here magnetic stimulation is applied to identified areas of the brain of the patient to bring relief.
  • Electromagnetic induction is also used to generate and transmit power.

Electrical Generator

An electrical generator reverses positive to negative polarity to produce an electric current.

Electrical Generator

Electrical Generator

An electrical generator is made up of a coil at a right angle to the magnetic field.

To unlock this lesson you must be a Study.com Member.
Create your account

  • Activities
  • FAQs

Electromagnetic Induction True or False Activity

This activity will help you assess your knowledge of the definition and variables that affect induction.

Directions

Determine whether the following statements are true or false. To do this, print or copy this page on a blank paper and underline or circle the answer.

1. Electromagnetic induction is the production of an electromotive force across an electrical conductor due to a changing electric field.

True | False

2. One of the best applications of magnetic induction is in swiping an ATM card on a card reader.

True | False

3. In data storage, the user data is stored in a strip and is in the form of many magnetized regions.

True | False

4. The magnetic field in a coil can be changed by varying the magnetic field strength.

True | False

5. Markel Faraday was an English scientist whose main discoveries include the principles underlying electromagnetic induction.

True | False

6. Due to their antiquity and simplicity, cassette tapes and floppy disks did not employ magnetic media.

True | False

7. Voltage strength is proportional to the number of wire turns and magnetic field changes.

True | False

8. Faraday conducted many experiments involving magnetic fields and insulators.

True | False

9. Induction flashlights are deemed as the most important invention that was created from the discovery of electromagnetic induction.

True | False

10. When you triple the number of turns, the induced voltage also triples.

True | False


Answer Key

  1. False, because the correct statement is, Electromagnetic induction is the production of an electromotive force across an electrical conductor due to a changing magnetic field.
  2. True
  3. True
  4. True
  5. False, because the correct statement is, Michael Faraday was an English scientist whose main discoveries include the principles underlying electromagnetic induction.
  6. False, because the correct statement is, Even in their antiquity and simplicity, cassette tapes and floppy disks employed magnetic media.
  7. True
  8. False, Faraday conducted many experiments involving magnetic fields and conductors.
  9. False, because the correct statement is, Generators are deemed the most important invention that was created from the discovery of electromagnetic induction.
  10. True

Where is electromagnetic induction used?

Electromagnetic induction is used in generators, transformers, hard drives, tablets, and also electric cars. . It also sees an application in the treatment of patients with mental disorders like hallucinations and depression by way of transcranial magnetic stimulation (TMS).

What is electromagnetic induction and how does it work?

In electromagnetic induction, a current is produced in a wire due to a change in the magnetic field.

For example, let us perform an experiment with a bar magnet and a coil. When the two are bought together there is a relative motion because of which there is a magnetic flux in the coil, this produces an electric current.

Register to view this lesson

Are you a student or a teacher?

Unlock Your Education

See for yourself why 30 million people use Study.com

Become a Study.com member and start learning now.
Become a Member  Back
What teachers are saying about Study.com
Try it risk-free for 30 days