Quick questions on Passive RC filters: low-pass, high-pass and cut-off frequency - WJEC A-Level Electronics

3short 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 the cut-off frequency?

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The cut-off (break) frequency is where the capacitor's reactance equals the resistance. At this frequency the output power has fallen to half its passband value, hence the half-power point.

What is q1?

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An RC low-pass filter has

R = 10\,\text{k}\Omega

and

C = 10\,\text{nF}

. Find the cut-off frequency. [2 marks]

What is q2?

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State the output voltage as a fraction of the input at the cut-off frequency, and the corresponding gain in decibels. [2 marks]

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