What is inductance and its formula

INDUCTOR

            Inductor are passive components consisting of coil of wire. The basic function of inductor is to store electrical energy in the form of magnetic field, when current flows through the inductor.

INDUCTANCE

                 Inductance is the electrical property of Inductors. The property of A.C circuits which opposes any change in the amount of current is called inductance.

UNIT IF INDUCTANCE

                  Its symbol 'L' and unit is 'henry' (H).

HENRY

           If a current changing at the rate of one ampere second , induces and average e/m/f of one volt in a conductor, the amount of inductance in the conductor will be one henry.

1x10^-3  Henries = 1 Milli Henry =1mH

1x10^-6  Henries = 1  Micro Henry = 1µH

1x10^-9  Henries = 1 Nano Henry = 1nH

Applications of  Inductors

• Tuning circuits
• Sensors 
• Store energy in a device
• Induction motors
• Transformers
• Filters 
• Chokes
• Relay

                                Some other topic of Inductor

## An inductor is commonly known as a choke.

## The components used for checking the flow of A.C is called a choke.

## Inductance of Inductor dependents on supply frequency

## Supply frequency high then impendance high

## Supply frequency low then impendance low

## Inductive circuit current lagging -90⁰ 

                                                    TYPES OF INDUCTOR

A) Depending upon the type of core material

          Aa) Air core

          Ab) Ferrite core

          Ac) Iron core

                 Ac) 1) Laminated iron core

                Ac) 2) Powdered iron core

B) Depending upon the control over inductance

           Ba) Fixd

           Bb) Variable

                   Bb) 1) Tapped 

                   Bb) 2) Continuous

C) Depending upon the Frequency range

         Ca) Low frequency Inductors (10Hz to 10KHz)

         Cb) High frequency Inductors  (100KHz and above)

 D) Depending upon the construction

        Da) Screened

        Db) Unscreened

AIR CORE INDUCTOR

            Ii is simply a coil of fine copper wire wound on a hollow cylindrical spool of an insulating material. It is made in the inductance range of the order of micro and milli henrys.

Air core coils have practically no losses from eddy currents or hysteresis.

USED

      Air core inductors are used in high frequency applications.

FERRITE CORE INDUCTOR

       In this case, coil of wire is wound on a solid core made of highly ferromagnetic substance called ferrite. They provide high value of flux density like iron, but have the advantage of being insulators. A ferrite core has minimum eddy current loss.

USED

      Ferrite core inductors are used for high to very high frequency application.

LAMINATED IRON CORE INDUCTOR

           It is formed using a group of individual lamination. Each lamination is insulated by a thin coating of iron oxide, silicon steel or varnish. This insulation increases the resistance reducing eddy current losses.

USED 

      These type of inductors are generally used for mains frequency of 50Hz to 60Hz and lower audio frequency range, up to 10KHz.

POWDERED IRON CORE INDUCTOR

       It consists of individual insulated granules pressed into one soil form called slug.

USED

     It is used to reduce the eddy currents in the core when used at radio frequencies.

SELF INDUCTANCE 

                       The property of one conductor which opposes any change in the amount of current is called self inductance.

 

Self inductance (L)=N.Ø / I

N= Number of turns of the coil.

Ø= Amount of flux passing through the coil, Wb.

I= current, amperes.

Mutual Inductance(M)

                    When two inductors L and L are placed side by side close to each other, although the two coils are not electrically connected. The two coils are said to be magnetically inter coupled. its called Mutual Inductance.

Mutual Inductance(M)= √L₁×L₂  

M=Mutual inductance.

L₁ = Self inductance  of first coil                

L₂   = Self inductance of second coil

Coefficient of coupling(K)

                      

                     The amount of mutual inductance between two coils depend upon, the self inductance of each coil and the amount of mutual flux between the two coils. The amount of mutual flux, that links both coils is dependent on the physical placement of the two coils its called coefficient of coupling.

Coefficient coupling(K)= Mutual flux between two coils / Total flux set up by one coil.

                 K=M/√L₁×L₂ 

Energy stored in an Inductor 

                        

                       When current passes through an inductor, magnetic flux is produced for which energy is supplied by  the voltage source. This energy is safely stored in the field itself and is recoverable.

Energy storage Inductor

  1÷2  × L × I² 

Induced e.m.f

 

 Induce e.m.f.(e)= -L×di÷dt

di÷dt= rate of change of current 

L= self inductance

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