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Component 1: Semiconductor Components
Quick questions on Diodes: the p-n junction, rectifier, Zener and LED - 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 the diode I-V characteristic?Show answer
The characteristic curve is flat (near zero current) for reverse and small forward voltages, then rises sharply once the forward voltage passes the threshold. The sharp knee at about is the diode's signature, and it is strongly non-ohmic: resistance is high below the threshold and low above it.
What are the four diode types?Show answer
Zener diode is designed to break down at a precise reverse voltage; run in reverse breakdown it holds that voltage almost constant and acts as a voltage regulator or reference.
What is q1?Show answer
State the approximate forward voltage at which a silicon diode begins to conduct, and explain what happens to the depletion layer at this point. [2 marks]
What is q2?Show answer
A red LED dropping is driven from a supply and should carry . Find the series resistor needed. [2 marks]
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