Automated systems in lighting

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Quick Questions

Shade in the A or B circle for each question.

1. Which sensor lets a street lamp switch on at dusk?

A Light sensor

B Pressure sensor

2. A security light comes on when someone walks past. Which sensor detects the movement?

A Infra-red motion sensor

B pH sensor

3. In an automated street lamp, what does the microprocessor do with the light sensor reading?

A Turns it into heat to power the lamp

B Compares it with a stored value and decides whether to switch the lamp on

4. Which part acts as the actuator in an automated lighting system?

A The switch or dimmer that turns the lamp on, off or down

B The light sensor that measures brightness

5. True or false: in automated lighting, someone must press a switch each time the light changes.

A True

B False

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1IF lightLevel < 30 THEN lamp ← ON		AIF 25 < 30 THEN lamp ← ON
2IF motion = TRUE THEN securityLight ← ON		BThe comparison is the wrong way round. The lamp would switch on in bright daylight, because the reading is high, not at dusk when it is low.
3The actuator in an automated light is the part that changes the lamp, such as a dimmer making it less bright		CAn infra-red motion sensor detects a person, so the microprocessor switches the security light on automatically
4Tracing a street light at dusk: the light sensor reading falls below the stored value, so the lamp is switched on		Ddimmer ← 40
5IF lightLevel > 30 THEN streetLamp ← ON		EThis is manual control, not automation. Automated lighting uses sensors and a microprocessor to switch lights without anyone touching a switch.
6Smart lamp turns on only when someone presses the wall switch		FA street lamp's microprocessor compares the light sensor reading with a stored value and switches the lamp on at dusk

Definitions

automated lighting

Fill in the Blanks

Complete each line of code by filling in the missing parts.

IF lightLevel _ darkValue THEN lamp ← ON ENDIF

IF infraRed = TRUE THEN securityLight ← __ ENDIF

IF lightLevel < darkValue ____ lamp ← ON ENDIF

IF phoneNearHome = TRUE THEN hallLight ← ON _____

lightLevel ← READ(lightSensor) IF __________ < 30 THEN lamp ← ON

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A WHILE TRUE

B level ← lamp.read()

C IF level < 30 THEN

D lamp ← ON

E ENDIF

F ENDWHILE

Question 2

A WHILE TRUE

B motion ← lightSensor.read()

C IF motion = TRUE THEN

D light ← ON

E ENDIF

Question 3

A IF level > 30 THEN

B lamp ← ON

C ELSE

D lamp ← OFF

E ENDIF

Question 4

A level ← lightSensor.read()

B IF level < 50 THEN

C 80 ← dimmer

D ELSE

E dimmer ← 0

F ENDIF

Question 5

A time ← clock.read()

B motion ← irSensor.read()

C IF time > 18 AND motion THEN

D light ← OFF

E ENDIF

Answer Key

Automated systems in lighting

Section A: Quick Questions

A — Light sensor

A — Infra-red motion sensor

B — Compares it with a stored value and decides whether to switch the lamp on

A — The switch or dimmer that turns the lamp on, off or down

B — False

Section B: Match the Pairs

IF lightLevel < 30 THEN lamp ← ON → A street lamp's microprocessor compares the light sensor reading with a stored value and switches the lamp on at dusk

IF motion = TRUE THEN securityLight ← ON → An infra-red motion sensor detects a person, so the microprocessor switches the security light on automatically

The actuator in an automated light is the part that changes the lamp, such as a dimmer making it less bright → dimmer ← 40

Tracing a street light at dusk: the light sensor reading falls below the stored value, so the lamp is switched on → IF 25 < 30 THEN lamp ← ON

IF lightLevel > 30 THEN streetLamp ← ON → The comparison is the wrong way round. The lamp would switch on in bright daylight, because the reading is high, not at dusk when it is low.

Smart lamp turns on only when someone presses the wall switch → This is manual control, not automation. Automated lighting uses sensors and a microprocessor to switch lights without anyone touching a switch.

Section C: Definitions

automated lighting — Lights switched on, off or dimmed by sensors and a microprocessor with no one touching a switch, e.g. a street lamp that comes on when its light sensor detects dusk.

Section D: Fill in the Blanks

IF lightLevel < darkValue THEN
    lamp ← ON
ENDIF

IF infraRed = TRUE THEN
    securityLight ← ON
ENDIF

IF lightLevel < darkValue THEN
    lamp ← ON
ENDIF

IF phoneNearHome = TRUE THEN
    hallLight ← ON
ENDIF

lightLevel ← READ(lightSensor)
IF lightLevel < 30 THEN
    lamp ← ON

Section E: Spot the Error

B — The light level must be read from the light sensor, not the lamp. The lamp is the actuator that switches on. The line should be level ← lightSensor.read().

B — A security light needs an infra-red motion sensor to detect movement. A light sensor only measures brightness. The line should be motion ← irSensor.read().

A — The street lamp should switch on when it is dark, so the light level is below the stored value. With > it would come on in daylight. It should be IF level < 30 THEN.

C — Assignment puts the value on the right into the variable on the left. The dimmer setting must be written as dimmer ← 80, not 80 ← dimmer.

D — In smart home lighting, the light should switch on when it is evening and the infra-red sensor detects someone. Setting it OFF defeats the purpose. It should be light ← ON.