Choke involve use of _____________

Question

Examoogle · Accepted Answer

Inductor

Explanation: A choke is a passive electrical component designed to block higher-frequency alternating current (AC) in an electrical circuit while allowing lower-frequency or direct current (DC) to pass. It is constructed using an inductor, which consists of a coil of insulated wire, often wound around a magnetic core to increase its inductance.

Working Principle: The principle relies on the property of self-induction defined by $V = L \frac{di}{dt}$. As frequency increases, the inductive reactance $X_L = 2\pi f L$ increases, effectively presenting a high impedance to high-frequency signals and creating a 'choking' effect. This allows it to act as a low-pass filter to smooth out ripples or suppress interference.

Key Formulas: $X_L = 2\pi f L$ — Inductive reactance formula; $V = L \frac{di}{dt}$ — Induced EMF in an inductor

Key Points: A choke provides high impedance to AC and low impedance to DC.; The core material (air, ferrite, or iron) significantly influences the inductance value.; Commonly used in ballast circuits for fluorescent lamps and as filter chokes in power supplies.

Advantages: Efficiently blocks high-frequency noise; Minimal power loss compared to resistive current limiting

Disadvantages: Can be bulky and heavy if iron-cored; Stores energy in a magnetic field, which can cause voltage spikes upon disconnection

Applications: Switch-mode power supplies (SMPS); Fluorescent lamp ballasts; Radio frequency (RF) decoupling circuits

Additional Info: The unit of inductance is the Henry (H).. Option A (Resistor) would cause significant power dissipation due to $I^2R$ heating.. Option B (Capacitor) provides low impedance to high frequencies, acting as a shunt, not a series choke.

Answer: C is correct — A choke is fundamentally an inductor used to impede or 'choke' high-frequency AC signals while passing DC.

Exam Tip: Always remember that in AC circuits, $X_L \propto f$, meaning chokes become more effective at blocking signals as the frequency of the input increases.

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