Which component is used to block higher frequency alternating current in an electrical circuit?

• A. Inductor iron core choke
• B. Fuse
• C. Push button switch
• D. AC plug

Answer: (A)

When you want to block higher frequency AC while letting DC or low-frequency signals pass, you rely on impedance that grows with frequency. An inductor, especially one with an iron core, does exactly that. The impedance of an inductor is X_L = 2πfL, so as frequency f increases, the opposing resistance to current grows. The iron core increases the inductance L by concentrating the magnetic flux, making the overall impedance much larger for high-frequency components. This is why an iron-core choke is effective at blocking high-frequency AC—it attenuates rapid current changes while allowing slower or steady currents to flow.

The other parts serve different roles: a fuse protects against overcurrent by interrupting the circuit when current is too high, a push-button switch simply opens or closes the circuit, and an AC plug is just a connector to supply power. None of them are designed to selectively block high-frequency signals the way an inductor-based choke does.