Eddy current class 12: defination , explanation, applications

  Eddy current is so important because it has many applications in our daily life so in this section we discuss about it(application of eddy current class 12) in below .
Application of  eddy current class 12

Eddy current defination

      When a metal is placed in a changing magnetic field the induced current circulate through the metal then induced current is know as eddy current.
Eddy current

         Now we understand eddy current in details : 
 We have seen that emf is induced in a a coil when magnetic flux link with it is changes.
     Same phenomenon has been observed in case of a solid piece of conductors. 
      Whenever there is a change in magnetic flux linked with the a conductor, current flowing through it in a closed circuits. These current are called as eddy current.

      Consider a cylinder of good conductor rotating in clockwise direction in a magnetic field extending from left to right. As a result of rotation, the right half of the cylinder moves down and left half moves up.

Defination of eddy current
       Applying Fleming's right hand rule, it can be concluded that the direction of induced current will be toward the reader in right half and away from him in the left half. These currents will keep on flowing so long as the rotation of the cylinder takes place.

         In various electrical machines like transformer, we have to use coils wound over shoft iron core. As current changes through the coil, the magnetic field and hence the magnetic flux linked with core changes.
     From  Eddy current defination we know that eddy current  will set up in this core, causing not only loss of energy but may damage the coil due to heating effect.
    In mechanical machine, unwanted energy loss takes place due to friction. In electrical machine, it takes place due to eddy currents.
   There we minimise the loss by using lubricant. Here we shall minimise the loss by using the core in the form of laminations having a fine coating insulation in between.
       Breaking up of bulk of iron core into into laminations decrease the magnitude of eddy current. 
       The laminations are made in such a way that their planes are at right angle to the direction of current. 
       The fine layer of insulation offer a large resistances to the current, thus minimising their value.

Application of eddy current Class 12 

1. In induction furnace 

        From Eddy currents definition we can see that eddy current can be used to build up a furnace for making alloy. Different metals to be mixed together, contain in a container, are placed in between the pole pieces of an electromagnet excited with AC of high frequency. 

        As magnetic field changes rapidly, the magnitude of eddy current set up in the metals is so large that they fuse into another due to the heat produced. 

2. Dead beat galvanometer 

      The coil of a moving coil galvanometer turns around a shoft iron core. When current passes through the coil, it gets deflected. 
       This results in production of eddy current in core which oppose the motion of coil.Thus ,the coil will not be oscillating for long time after the current is cut off It turns to equilibrium quickly.
3. AC motor 
        In Case of a AC motor a rotating magnetic field is used. Eddy currents will set up in a metallic cylinder placed in the region of rotating magnetic field. 
        Due to these current, the cylinder, while trying to decrease relative displacement, starts rotating. This is one of the popular application of eddy current class 12.
4. Speedometer 
         A magnet adjust inside a metallic drum is connected to a axle of wheels of the vehicle. Due to motion of vehicle, the magnet rotates setting up eddy currents in drum. 
     The drum oppose motion of magnet and receives a recoil in this process. The recoil of the drum is indicate on a scale with the help of a pointer, thus ,giving the speed of vehicle. 
5. Magnetic break 

          A metallic drum attach with the  axle of wheels rotate with the speed of vehicle or wheel. When we want to stop the vehicle, a strong magnetic field is applied to drum. 

          The eddy current, set up in the drum, tend to oppose the rotation of drum, thus causing resistance to motion. This is an interesting application of eddy current class 12.
6. Inductothermy 
            The property of eddy currents that they produce heat has also been utilised for localised heating of tissues of body. 

          Eddy current play a role analogous to that played by friction in machines. There we minimised friction(resistance)by lubricant, while here we try to minimise the loss of energy using the core in lamination form in application of eddy current class 12. 

This is all about Eddy current defination and explanations and application of eddy current class 12.  If you have any queries you can ask in comment box. 
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