Aim

To study the phenomenon of Electromagnetic Induction

 

Introduction

Electro Magnet:
An electromagnet is a type of magnet in which the magnetic field is produced by electric current. The magnetic field disappears when the current is turned off.

INDUCTION:
This process of generating current in a conductor by placing the conductor in a changing magnetic field is called induction.

Electromagnetic induction:
Electromagnetic induction is the production of a potential difference (voltage) across a conductor when it is exposed to a varying magnetic field. Electromagnetic induction is when an electromagnetic field causes molecules in another object to flow. Induction can produce electricity (in coils), heat (in ferrous metals), or waves (in a radio transmitter).

Finally, it is referring to the phenomenon where an emf is induced when the magnetic flux linking a conductor change.

Magnetic Flux is defined as the product of the magnetic flux density and the area normal to the field through which the field is passing. It is a scalar quantity and its S.I. unit is the weber (Wb).

 

Principle

Electromagnetic induction (or sometimes just induction) is a process where a conductor placed in a changing magnetic field (or a conductor moving through a stationary magnetic field) causes the production of a voltage across the conductor. This process of electromagnetic induction, in turn, causes an electrical current, it is said to induce the current.

 

Theory

INVENSION:
Michael Faraday is generally credited with the discovery of induction in 1831 though it may have been anticipated by the work of Francesco Zantedeschi in 1829. Around 1830 to 1832, Joseph Henry made a similar discovery, but did not publish his findings until later.

Induced e.m.f:
If magnetic flux through a coil is altered then an e.m.f. will be generated in the coil. This effect was first observed and explained by Ampere and Faraday between 1825 and 1831. Faraday discovered that an e.m.f. could be generated either by,
(a) moving the coil or the source of flux relative to each other or
(b) By changing the magnitude of the source of magnetic flux.

Note that the e.m.f. is only produced while the flux is changing.

 For example, consider two coils as shown in Following Figure.

Working and Construction

Current is produced in a conductor when it is moved through a magnetic field because the magnetic lines of force are applying a force on the free electrons in the conductor and causing them to move. This process of generating current in a conductor by placing the conductor in a changing magnetic field is called induction. This is called induction because there is no physical connection between the conductor and the magnet. The current is said to be induced in the conductor by the magnetic field. One requirement for this electromagnetic induction to take place is that the conductor, which is often a piece of wire, must be perpendicular to the magnetic lines of force in order to produce the maximum force on the free electrons. The direction that the induced current flows is determined by the direction of the lines of force and by the direction the wire is moving in the field. In the animation above the ammeter (the instrument used to measure current) indicates when there is current in the conductor.

Lenz’s Law:
When an emf is generated by a change in magnetic flux according to Faraday’s Law, the polarity of the induced emf is such that it produces a current whose magnetic field opposes the change which produces it. The induced magnetic field inside any loop of wire always acts to keep the magnetic flux in the loop constant. In the examples below, if the B field is increasing, the induced field acts in opposition to it. If it is decreasing, the induced field acts in the direction of the applied field to try to keep it constant.

 

Application of Electromagnetic Induction

Electrical Generator:
The EMF generated by Faraday’s law of induction due to relative movement of a circuit and a magnetic field is the phenomenon underlying electrical generators. When a permanent magnet is moved relative to a conductor, or vice versa, an electromotive force is created. If the wire is connected through an electrical load, current will flow, and thus electrical energy is generated, converting the mechanical energy of motion to electrical energy.

Electrical transformer:
The EMF predicted by Faraday’s law is also responsible for electrical transformers. When the electric current in a loop of wire changes, the changing current creates a changing magnetic field. A second wire in reach of this magnetic field will experience this change in magnetic field as a change in its coupled magnetic flux, dΦ_B/dt. Therefore, an electromotive force is set up in the second loop called the induced EMF or transformer EMF. If the two ends of this loop are connected through an electrical load, current will flow.

 

Observation

• Magnet is moved at certain rate and certain voltage is produced.
• Magnet is moved at faster rate and creating a greater induced voltage.
• Magnet is moved at same speed through coil that has greater number of turn and greater voltage is induced.
•  

Conclusion

Faraday’s Law of Electromagnetic Induction, first observed and published by Michael Faraday in the mid-nineteenth century, describes a very important electro-magnetic concept. Although its mathematical representations are cryptic, the essence of Faraday’s is not hard to grasp: it relates an induced electric potential or voltage to a dynamic magnetic field. This concept has many far-reaching ramifications that touch our lives in many ways: from the shining of the sun, to the convenience of mobile communications, to electricity to power our homes. We can all appreciate the profound impact Faraday’s Law has on us.

 

Application of Electromagnetic Induction in Real Life

The principles of electromagnetic induction are applied in many devices and systems, including:

• Electrical generators
• Induction motors
• Induction sealing
  
• Inductive charging
• Transformers
• Wireless energy transfer
• Wireless charger

   

Bibliography

• Wikipedia.co
• Google search engine
• www.youtube.com/knowledgecycle
• www.knowledgecycle.in
• Physics NCERT book for class XII