eddy currents - the concept we should know.

Views

eddy currents

Most of the people among you may be feeling bored when they be hearing the name of "eddy currents ". You may ignore this concept but you don't know that eddy currents basically have a good relationship with you. Now the question is how?

Don't worry! I wanna make you aware about this concept. So what you have to do is to simply read it and understand.

your relationship with eddy currents is hidden in this article. Hope you get it .

eddy currents

Definition of eddy currents or Foucault currents :

The induced circulating currents produced in a metal due to the change of magnetic flux linked with the metal are called eddy currents. The eddy currents  are also known as Foucault currents. 

The direction of eddy currents is given by Lenz's law.

For example :

Here in the below given figure, you can see that when a metallic block is placed in a non uniform magnetic field eddy currents are produced.

eddy currents

Experimental Demonstration of eddy currents. 

eddy currents experiment

eddy currents

Jumping disc:

An aluminum disc is placed over the core of an Electro-magnet. when currents flows in the circuit means after closing the circuit, the disc jumps up to a certain height. when the current starts increasing through the solenoid, the magnetic flux along the solenoid axis also gets increasing. Due to the changes in magnetic flux, induced currents means eddy currents are produced in the disc and it gets slowly magnetised. If the upper core of the Electro-magnet achieves North polarity, then as far as Lenz's law is considered, it's lower face means the disc must achieve North polarity. Due to this repulsive force between the lower face of the disc having North polarity and upper face of the core of disc also having North polarity, the disc jumps up-to a certain height. 

Read 👉: P-N junction diode

eddy currents

Disadvantages of eddy currents:

Eddy currents basically have three main disadvantages or we can say undesirable effects. All the three undesirable effects are discussed below ;

1) During the production of eddy currents especially in a metallic block, a large amount of energy is lost in the form of Heat.

2) The insulation used in the machine or appliance is completely  braked  during the production of heat by eddy currents.  

3) Unwanted dampening effects may be caused by eddy currents.

eddy currents

How to minimise the losses due to eddy currents?

As we know that the metallic cores are used in electrical devices like transformers, dynamo, choke etc. 

A large amount of eddy currents are produced in the core ,due to the change of magnetic field which in turn results in the production of large amount of heat in the core. This results into the loss of useful amount of energy. 

To minimise the loss of amount of energy produced by eddy currents, the solid metallic core is replaced with a large number of thin sheets. These sheets are eclectically insulated from one another and are called as laminations. And the core is called laminated core. The arrangement of these sheets is actually parallel to the magnetic flux. Hence the insulation breaks the paths of eddy currents and keeps the eddy currents restricted to the individual sheets. 

Finally the loss (H=I²RT) due to eddy currents is minimised to a large extent. 

Read 👉: Fundamental Forces in Nature 

eddy currents

Advantages or applications of eddy currents:

1) Induction Furnace:

Induction furnace is based on the heating effect of eddy currents  . It is used to separate metals from their ores and to make some alloys. 

2) Speedometer :

As we all know the device which measures the instantaneous speed of vehicles. Speedometer is also based on the concept of eddy currents  . 

3) Energy Meters :

Energy meters are used to measure the consumption of electricity. This meter basically runs on the concept of eddy currents. 

4) Diathermy:

Diathermy is a process of heating of tissues in a human body .Eddy currents are used for the localised heating of tissues in human body. 

5) Electromagnetic breaks :

The concept of eddy currents is used to control the speed of electric trains.


This article provides you information related with eddy currents including the advantages and disadvantages of eddy currents.