Concept of SELF INDUCTUNCE.

What is SELF INDUCTUNCE?

⇨ If an time varying current is passing through the Coil or Winding, it produces the time varying flux this flux is linked with it self and voltage is induced in the coil or Winding is called as a SELF INDUCED VOLTAGE.

                   V = L di/dt ................(1)

Fig.(a) SELF INDUCED VOLTAGE

• Why inductor oppose the rate of change of current?

➝we know that due to time varying current self induced voltage is induced in coil, this is shown by V. Magnetic field within it is try to maintain its value constant. But if at any intant supply current is disturb then this self induced voltage create a current which Oppose the rate of change of supply current (according to Lenz's law).

Now, the inductor L is expressed as,

                          L = NΦ/ I ................(2)

Where; N = Number of turns of Coil

               Φ = Flux linkage with coil

               I = Current passing through the

Coil

 

• Substitute equation number (2) in (1)......

                            I = NΦ/L ..................(3)

Now putting the value of I in equation number (1) we get.........

               V = L × d (NΦ/L) / dt

             ∴  V = L × 1/L × N  dΦ/dt

             ∴ V = N × dΦ/dt ..............(4)

• Comparing equation number (1)& (4)........

           L × di/dt = N × dΦ/dt

As seen "dt" is cancelled out ......

Finally we get value of INDUCTUNCE "L" is......

                       L = N × dΦ/ di 

        ............Thank you 🙂............