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Inductor. Inductor. Inductor is a passive electric device that store energy in its Magnetic field when a current flows through it A coil of wire wound on a Ferromagnetic core Air core Inductor, iron core inductor Circuit representation is. L. i. v L. +. Inductive Circuit.
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Inductor • Inductor is a passive electric device that store energy in its Magnetic field when a current flows through it • A coil of wire wound on a Ferromagnetic core • Air core Inductor, iron core inductor • Circuit representation is Dept of E & E Engg, MIT Manipal
L i vL + Inductive Circuit • Inductance (L) : Property which opposes the rate of change of current. • The voltage induced in the inductor is proportional to the rate of change of current flowing through it • eL = L (di/dt) • Unit is Henry (H). • This proportionality constant is the self inductance or inductance (L) Dept of E & E Engg, MIT Manipal
Equivalent Inductance In series In parallel Dept of E & E Engg, MIT Manipal
Growth of current in an Inductive Circuit Dept of E & E Engg, MIT Manipal
Growth of current in an Inductive Circuit … • Time Constant, = L/R • Time taken by the current through the inductor to reach its final steady state value, had the initial rate of rise been maintained constant Dept of E & E Engg, MIT Manipal
Decay of current in an Inductive Circuit … • Initial current is through inductor is I0 = V/R • At t =0, switch is moved from position a to b Dept of E & E Engg, MIT Manipal
Decay of current in an Inductive Circuit … Dept of E & E Engg, MIT Manipal
Energy stored in an Inductor Dept of E & E Engg, MIT Manipal
Example In the network shown in figure, the switch is closed to position 1 at t = 0 and is moved to position 2 at 10 ms. Determine iL(t) & sketch it. • Switch in 1; for 0 t 10 ms • i1 (t) = (V/R) * (1 – e -(R t/L)) = 1- e -100 t • At ‘t’ = 10 ms; I1 = 0.632 A • Switch in 2; t > 10 ms • i2 (t) = I1 * e -(R1 t/L) = 0.632 e-250(t – 0.01) Dept of E & E Engg, MIT Manipal