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WalesElectronicsQuick questions
Component 1: AC Circuits and Passive Filters
Quick questions on AC signals and reactance: RMS, capacitive and inductive reactance - WJEC A-Level Electronics
4short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What is capacitive reactance?Show answer
Reactance is the AC opposition (in ohms) of a capacitor. Because is inversely proportional to frequency, a capacitor passes high frequencies and blocks low frequencies and DC (at DC, , the reactance is infinite, so no current flows once charged).
What is inductive reactance?Show answer
An inductor's reactance is proportional to frequency, so it blocks high frequencies and passes low frequencies and DC. This opposite behaviour to a capacitor is what lets the two be combined to select frequency bands.
What is q1?Show answer
A sine wave has an RMS voltage of . Find its peak voltage. [2 marks]
What is q2?Show answer
State whether a capacitor or an inductor passes DC, and explain in terms of reactance. [2 marks]
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