O-LevelComputer ScienceAutomated and emerging technologies2210/12 · Oct/Nov 2016 · Q119 Marks
11 A security system is installed in a house. A hexadecimal number is entered to activate or deactivate the alarm. (a) The alarm code is set to hexadecimal number 2 A F Show how this number would be stored in a 12-bit binary register. (b) Identify two sensors that the security system could use to detect intruders. Describe how each sensor could be used in the security system. Sensor 1 Description Sensor 2 Description
- (a)The alarm code is set to hexadecimal number 2 A F Show how this number would be stored in a 12-bit binary register.[3]
- (b)Identify two sensors that the security system could use to detect intruders. Describe how each sensor could be used in the security system. Sensor 1 Description Sensor 2 Description[6]
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Mark scheme
Marking points from the official mark scheme (Oct/Nov 2016). The mark or mark type is shown in brackets.
- [3] (a) 1 mark per nibble
- 0010 1010 1111
- [6] (b) 1 mark for identification of each sensor, max 2 for each description
- Sensor: Infrared/motion sensor
- Description: Receives infrared rays/heat; Sends data to microprocessor; Receives microwaves; Placed in the corner of a room, across a doorway; Used to detect the heat of an intruder // used to detect if an infrared beam has been broken by an intruder
- Sensor: Pressure sensor
- Description: Receives current if circuit created // stops receiving current if circuit is broken; Sends data to microprocessor; Placed on a window/door, at the entrance; Used to detect a change in pressure
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