A security light system is used by a factory. The light only comes on when it is dark and when movement is detected. The light will stay on for 1 minute before switching off. Sensors and a microprocessor are used to control the security light system.

Mark scheme

Marking points from the official mark scheme (May/June 2021). The mark or mark type is shown in brackets.

1. [1] Light sensor
2. [1] Motion sensor // infra-red sensor
3. [1] Sensors send data to microprocessor
4. [1] Data is converted to digital (using ADC)
5. [1] Microprocessor compares data to stored value(s)
6. [1] if one value or neither values are within range/out of range/match no action is taken
7. [1] If both values are out of range/in range/match microprocessor sends signal to switch light on
8. [1] 1-minute timer is started
9. [1] Actuator used to switch on/off light
10. [1] When timer reaches 1 minute, microprocessor sends signal to switch light off
11. [1] Whole process is continuous