Humidity sensor

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Quick Questions

Shade in the A or B circle for each question.

1. What does a humidity sensor measure?

A The amount of water vapour in the air

B The amount of water in the soil

2. Is a humidity sensor an input device or an output device?

A Input device

B Output device

3. Which place would use a humidity sensor to check the moisture in the air?

A A barcode checkout

B A weather station

4. Why might a greenhouse use a humidity sensor?

A To keep the air moist enough for the plants to grow well

B To measure how loud the plants are

5. An air conditioning system uses a humidity sensor. What data does the sensor send to the microprocessor?

A Readings of how bright the room is

B Readings of how much water vapour is in the air

Match the Pairs

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

Left column		Right column
1humidity sensor		AIF humidity > 70 THEN start_dehumidifier
2humidity = readSensor()		BIF humidity < 60 THEN start_mister
3A greenhouse uses a humidity sensor to keep the air moist enough for plants		CAn input device that measures the amount of water vapour in the air
4An air conditioning system uses a humidity sensor to remove extra water vapour from the air		DA humidity sensor measures water vapour in the air, not water in soil. A moisture sensor is used for soil.
5A humidity sensor measures the amount of water in the soil		EStores the water vapour reading from the humidity sensor in a variable
6A weather station uses a humidity sensor to measure air temperature		FA humidity sensor measures moisture in the air. Air temperature needs a temperature sensor.

Definitions

humidity sensor

Fill in the Blanks

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

humidity _ GetHumidity()

IF humidity _ 70 THEN OUTPUT "Turn on air conditioning" ENDIF

IF humidity < 40 THEN ______ "Start the greenhouse sprayers" ENDIF

WHILE humidity > 60 DO humidity ← GetHumidity() ________

weatherHumidity ← GetHumidity() OUTPUT _______________

Spot the Error

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

Question 1

A humidity ← READ_SENSOR()

B IF humidity < 70 THEN

C OUTPUT "Too humid"

D ENDIF

Question 2

A WHILE TRUE

B h ← READ_HUMIDITY()

C IF h > 40 THEN

D TURN_ON(humidifier)

E ENDIF

F ENDWHILE

Question 3

A humidity ← READ_TEMPERATURE()

B IF humidity > 80 THEN

C OPEN_VENT()

D ENDIF

Question 4

A h1 ← READ_HUMIDITY()

B h2 ← READ_HUMIDITY()

C total ← h1 + h2

D average ← total / 3

E OUTPUT average

Question 5

A h ← READ_HUMIDITY()

B IF h > 60 THEN

C STATUS ← "damp"

D TURN_ON(humidifier)

E ENDIF

Answer Key

Humidity sensor

Section A: Quick Questions

A — The amount of water vapour in the air

A — Input device

B — A weather station

A — To keep the air moist enough for the plants to grow well

B — Readings of how much water vapour is in the air

Section B: Match the Pairs

humidity sensor → An input device that measures the amount of water vapour in the air

humidity = readSensor() → Stores the water vapour reading from the humidity sensor in a variable

A greenhouse uses a humidity sensor to keep the air moist enough for plants → IF humidity < 60 THEN start_mister

An air conditioning system uses a humidity sensor to remove extra water vapour from the air → IF humidity > 70 THEN start_dehumidifier

A humidity sensor measures the amount of water in the soil → A humidity sensor measures water vapour in the air, not water in soil. A moisture sensor is used for soil.

A weather station uses a humidity sensor to measure air temperature → A humidity sensor measures moisture in the air. Air temperature needs a temperature sensor.

Section C: Definitions

humidity sensor — An input device that measures the amount of water vapour (moisture) in the air. Used in weather stations, greenhouses and air conditioning systems.

Section D: Fill in the Blanks

humidity ← GetHumidity()

IF humidity > 70 THEN
    OUTPUT "Turn on air conditioning"
ENDIF

IF humidity < 40 THEN
    OUTPUT "Start the greenhouse sprayers"
ENDIF

WHILE humidity > 60 DO
    humidity ← GetHumidity()
ENDWHILE

weatherHumidity ← GetHumidity()
OUTPUT weatherHumidity

Section E: Spot the Error

B — The message says the air is too humid, so the test must catch HIGH readings. It should be IF humidity > 70 THEN.

C — The humidifier should only switch on when the air is too dry, which means a LOW reading. It should be IF h < 40 THEN.

A — A humidity sensor measures water vapour in the air, not temperature. The line should read the humidity sensor: READ_HUMIDITY().

D — Two readings were added together, so the total must be divided by 2 to get the average. It should be average ← total / 2.

D — When the air is too humid, an air conditioning system must remove moisture. A humidifier adds moisture, so it should be TURN_ON(dehumidifier).