Applications and Working of Electromagnetic Induction

When there is a continuous variation in the magnetic flux going through a coil, an electric current is produced in the coil. The electric current generated is called electromagnetic induction, and the force generated by it is called electromagnetic force.

The common devices that operate on the principle of electromagnetic induction are:

• AC generator 
• DC generator 
• Transformer

Common Applications/Examples of Electromagnetic Induction 

Electromagnetic induction is used in various devices, some of which are mentioned here:

• Security Gates: You must have observed that people are made to walk through a security gate in various public/private places, like buildings and complexes. The gate is an upright coil of wire which produces a weak AC (alternating current) magnetic field. If a considerable quantity of metal is carried through the gate, the magnetic flux associated with the coil triggers an alarm.
• ATM Card Scanners: Electromagnetic induction occurs in ATM card scanners when the magnetic strip of an ATM card is swiped through a scanner. When an ATM card is swiped through a card reader, a change in magnetic flux is produced in one direction, generating the induced EMF (electromotive force). The electric current received by the pickup coil produces signal amplification and translates it into the binary code, which makes it readable by the computer.
• Tape Recorder: The tape recorder used for listening to songs or recording voices works on the principle of electromagnetic induction. It consists of a piece of plastic tape coated with travel iron oxide and is magnetised more in some parts than in others. When the tape touches a small coil of wire (head of the tape recorder), the magnetic field created by the tape changes, leading to the generation of current in the small coil of wire.
• Induction Stove: The induction stove used for cooking also works on the principle of electromagnetic induction. A conducting coil is kept right below the cooling coil to reduce the temperature. It carries the alternating current so that AC produces an alternating magnetic field. When a metallic pan containing water is placed over it, the fluctuating magnetic field under it passes the base exterior of that pan, and an electromotive force is induced in it.

Examples of Electromagnetic Induction: DC Generators

DC generators, which work using electromagnetic forces, are a perfect example of electromagnetic induction. It is a device that converts mechanical energy into electrical energy (Direct Current). Direct current is the current that is unidirectional and does not change its magnitude. It works on the principle of electromagnetic induction (EMI).

It works mainly on two principles:

1. Faraday’s Law of Induction: Faraday’s Law of Induction is a fundamental law of electromagnetism forecasting. It explains how a magnetic field will work with an electric circuit to produce a phenomenon of an electromotive force, called electromagnetic induction.
2. Fleming’s Right-hand Rule: According to this rule, the thumb represents the direction of motion of the conductor, the first finger indicates the direction of the field (north to south), and the second finger indicates the direction of the induced current. The direction of the induced current will be the direction of the conventional current moving from positive (+) to negative (-).

A generator that gives rise to direct current from mechanical energy is called a DC generator (or dynamo) using the principle of electromagnetic induction. In the past, this was the only convenient way to produce electrical energy.

Workings of a DC Generator: If a conductor cuts magnetic lines of force, the electromagnetic force is generated in the conductor, and the electromagnetic force produced will vary with the number of magnetic lines of force, the number of conductors (i.e. the number of coil windings), and the speed at which the conductor cuts the lines of magnetic. The current generated is then assembled by using an external electric circuit. If a conductor (say coil) is rolled in a clockwise direction between the north and south poles of a magnet, EMF will be produced in the direction as stated in Fleming’s right-hand rule.

A DC generator is generally comprised of the following parts:

• Pole cores: They become the north and south poles of a magnet when the electric current energy flows through the conducting coils. They help in creating the magnetic field, which is necessary to induce magnetic flux. The majority of the DC generators have 4 poles. 

• Field windings: It is used as an insulating medium to wound wire in coil form and fix around the pole cores. It generates the magnetic field, which is crucial to provoke the DC generator.

• Armature: It is a shaft that rotates inside the cores of the pole and produces the EMF (electromotive force). It consists of a rotating shaft with the armature coil at the centre.

• Commutator: It turns Alternating Current to Direct Current. It makes sure that the current or stream of electrons flows in the form of DC.

• Brushes: It contacts against the commutator and passes the current produced in the armature to the field coil and the outside of the generator, which eventually results in the generation of electromagnetic force. It is made up of carbon.

Conclusion

This article gives an insight into the working mechanism of electromagnetic induction. This contains the name of some of the basic applications of electromagnetic induction, which makes use of the electromagnetic force produced using this principle to serve its purpose. We have discussed so far the application of electromagnetic induction in DC generators in detail and also in the ATM scanners, tape recorders, induction stoves, etc.