Document page
Computer Science IGCSEPDF 78
142 pagesrevision 46930
PDF 78
Page image rendered from the stored file at 110 dpi; it sharpens as you zoom. Outlines are placed from each region’s stored position on the page (612 × 792 pt).
readable
Source of this text: embedded text layer. The better of the embedded text and OCR is kept.
●
●
An automatic street-lighting system switches lights on at sunset and off at sunrise.
○ Describe how sensors and a microprocessor control this process.
An automatic security system uses an infrared sensor to detect movement.
○ Describe how this system operates when an intruder is detected.