Inductor is also a energy strong device just like a capacitor. The both devices are linear. Unless like resistor, they both can store energy. This energy can be used later on , at someplace else .

Inductor works on the principal of induction. Depending on its manufacturing and size, it may have a inductance ranging from micro henries to henries,.

Physical Structure of Inductor

Lets say I have core with a magnetic permeability of μ [permeability is the measure of the ability of a material to support the formation of a magnetic field within itself.]

No lets turn some coils around this core . Lets say the number of turn on a coil is represented by N

Now the above structure is a complete inductor. In general an inductor can be made by turning a wire in to coils.

So lets say that a current i enters the wire, and the potential difference between the wires is represented by v

Lets sat the area of the core is A, and the circumfrence is represented by l

Lets say λ is the total magnetic flux [Magnetic flux is the number of magnetic field lines (also called “magnetic flux density”) passing through a closed surface (such as a conducting coil). The SI unit of magnetic flux is the weber (Wb) (in derived units: volt-seconds).]

So till far we have defined following parameter

• λ Magnetuc flux
• A Area of core
• l Cirumference of core
• N Number of turns of coal
• i currnet entering wire
• v Potential difference
• μ magnetic permeability
• so L (inductance can be defined as

L= ……….Equation 1

If a inductor having a large number of inductance is to be constructed in a small physical size, it must have a large number of turns , and very fine wire. A large number value od inductor means that it would also have a large resistance parameters. So while using large value of inductors, we also need to take consideration of their resistances.

Symbol

Relation of Magnetic Flux and Inductor.

…….. Equation 2

 

Where

• λ=magnetic Flux [webbers]
• L=indutor [Henry]
• i= currenet [A]

Now in the above equation all variables have power 1. Hence it is a linear equation so L is a linear device

Volatge and Current across Inductor

One of the important property of inductor is that it tries to resist changes in current parameter of a circuit.

We know that λ has a unit of webber which is equal to voltage.sec . Using this paremter we can easily finding voltage acroos a concductor

So

v= Equation 3

Now we can use equation 2 to insert values of  λ in equation 3

Inserting value of λ to equation 3, we get

v= Equation 4

or

v= Equation 5

Current in a Inductor

By taking integral of equation 5 we can easily find the value of current in a inductor .

i= Equation 6

Energy Stored in a Inductor

We know that unlike resistors, inductors can store energy . . So lets recal some old equation first

v=

We have already established that power is product of voltage and currnet .

P=i x v

One must notice that here voltage and current are both time variable . Plugging in the values of voltage in power equation .

Energy Stored in Inductor .

The energy stored in a capacitor is given by