Extra exam question E6F05
Subelement E6, CIRCUIT COMPONENTS· Group E6F
Which of the following describes an optical shaft encoder?
- A.A device that detects rotation by interrupting a light source with a patterned wheel (correct answer)
- B.A device that measures the strength of a beam of light using analog-to-digital conversion
- C.An optical computing device in which light is coupled between devices by fiber optics
- D.A device for generating RTTY signals by means of a rotating light source
WhyAn optical shaft encoder detects rotation by interrupting a light source with a patterned wheel. An optical shaft encoder detects rotation by using a patterned wheel, attached to a rotating shaft, to periodically interrupt a light beam as the shaft turns, with a sensor counting those interruptions to track position or speed, answer A. It isn't measuring light beam strength through analog-to-digital conversion, isn't an optical computing device linked by fiber optics, and it isn't a technique for generating RTTY signals, none of those describe how a shaft encoder actually works.
Published 2026-08-28 · Last updated 2026-08-28 · Question text is verbatim from the 2024-2028 NCVEC Element 4 pool (public domain); the explanation above is original writing, see our methodology.
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