Introductory Electronics
Physics · 50 practice questions
Distinction between metals, semiconductors and insulators (band gap); intrinsic and extrinsic (n-type and p-type) semiconductors; uses of semiconductors and diodes in rectification and transistors in amplification; elementary knowledge of diodes and transistors.
- Differentiate between conductors, semiconductors and insulators.
- Distinguish between intrinsic and extrinsic (n-type and p-type) semiconductors and between electron and hole carriers.
- Analyse diodes and transistors and relate diodes to rectification and transistors to amplification.
Try a few questions
- Practice question 1
A conductor typically has a very small (or overlapping) band gap, allowing electrons to
- A.remain permanently fixed within the valence band at all temperatures
- B.require an enormous amount of energy to conduct at all
- C.behave identically to electrons within a good insulator
- D.move freely into the conduction band even at room temperature
Show the answer
D. move freely into the conduction band even at room temperature
A negligible band gap is exactly what lets a conductor's electrons flow so readily.
- Practice question 2
A light-emitting diode (LED) emits light when current flows through it in the
- A.reverse bias direction, as electrons and holes are kept apart
- B.either direction equally, with identical light output
- C.absence of any current at all
- D.forward bias direction, as electrons and holes recombine at the p-n junction
Show the answer
D. forward bias direction, as electrons and holes recombine at the p-n junction
Forward-biased recombination of electrons and holes at the junction is exactly what releases energy as light in an LED.
- Practice question 3
A transistor is mainly used for
- A.the storage of electric charge over an extended period
- B.amplification, allowing a small input signal to control a much larger output signal
- C.the generation of a magnetic field from a steady direct current
- D.the conversion of alternating current into a completely constant frequency
Show the answer
B. amplification, allowing a small input signal to control a much larger output signal
A transistor's core function is boosting a weak input signal into a stronger output signal.
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