Inductor does not allow sudden changes in?

Question

Examoogle · Accepted Answer

Current

Explanation: An inductor resists sudden changes in current because it generates an induced electromotive force (EMF) that opposes the change in magnetic flux through its coils. According to Lenz's Law, this back EMF acts to maintain the pre-existing state of current flow.

Working Principle: When current through an inductor changes, the magnetic field linked with the inductor changes, inducing a voltage $v = L \frac{di}{dt}$. If the current were to change instantaneously ($dt 	o 0$), the induced voltage would become infinite, which is physically impossible in a real circuit. Thus, the inductor ensures the current remains continuous.

Key Formulas: $v(t) = L \frac{di(t)}{dt}$ — Governing equation showing voltage dependency on rate of change of current; $i(t) = \frac{1}{L} \int v(t) dt$ — Integral form showing current as the accumulation of voltage over time

Key Points: Inductors act as open circuits for DC steady-state analysis after switching transients.; The energy stored in an inductor is $W = \frac{1}{2}LI^2$.; Current continuity is the fundamental property utilized in buck converters and smoothing filters.

Advantages: Provides surge protection in power electronic circuits; Used for filtering high-frequency noise

Disadvantages: Inductors cause voltage spikes when circuit paths are broken abruptly; Physical size and weight can be high for large inductance values

Applications: Buck/Boost Power Converters; Radio Frequency Tuning Circuits; Electromagnetic Relays

Additional Info: Capacitors are the dual of inductors; they oppose sudden changes in voltage ($i = C \frac{dv}{dt}$).. Option A is incorrect because capacitors, not inductors, oppose sudden changes in voltage.

Answer: B is correct — An inductor opposes any instantaneous change in the current flowing through it due to the generation of a back EMF.

Exam Tip: Always remember the mnemonic: 'CIVIL' - In a Capacitor (C), Current (I) leads Voltage (V); in an Inductor (L), Voltage (V) leads Current (I).

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