You work as a Chief Security Officer for Tech Perfect Inc. The company has an internal room without any window and is totally in darkness. For security reasons, you want to place a device in the…

Question

Options

• APhotoelectric motion detector
• BBadge
• CClosed-circuit television
• DAlarm

• A
  80% (49)
• B
  3% (2)
• C
  10% (6)
• D
  7% (4)

Explanation

A photoelectric motion detector is ideal for a dark, windowless room because it detects intrusions using infrared (heat-based) sensing or light-beam interruption - neither of which requires visible light to function, making it perfectly suited for total darkness.

Why the distractors are wrong:

• B. Badge - An access control credential, not a room-monitoring device; it controls entry but cannot detect activity inside a room.
• C. CCTV - Standard cameras require light to capture usable footage; a dark, windowless room renders conventional CCTV blind.
• D. Alarm - An alarm is an output device (it signals a breach); it has no detection capability on its own.

Memory tip: Think "Motion detectors don't need eyes." Unlike cameras (which need light) or badges (which need people to use them), a photoelectric/PIR sensor silently "feels" heat signatures and movement in complete darkness - making it the only truly passive, light-independent detection option in the list.

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