Sensors, tiny computers and keeping devices healthy
Week 23 · Theme 4 Software Projects, Lessons 1–2 Explorer in Action; How Digital Devices Work · 3 lessons
1
Sensors that watch and save energy
ICT P5 Term 2, Theme 4: pp. 44–53
GoalExplain what a sensor does and how sensors and a program can save electricity.
New words
sensor · a device that measures something and sends the information to a computerthermostat · a switch that measures temperature and turns a machine on or offenergy · the power that makes machines work, such as electricityremote sensing · collecting information about the Earth from far away, for example from space
Explanation
A sensor is like a pair of eyes for a computer. A thermostat is one kind: it measures the temperature, and when a room is cool enough it switches the air conditioner off. Now imagine many fridges and air conditioners in a town, each with a sensor. The sensors send numbers to a computer, and a program decides how to use electricity wisely. It also records how much electricity is used. Electricity use changes through the day: in hot summer afternoons everybody uses air conditioners, so the use is highest. Knowing this, engineers can share electricity better and waste less. In Egypt, data from remote sensing help engineers use water well in newly farmed land.
Worked examples
A small thermostat in a fridge measures 4 degrees. The program says the fridge is cold enough, so the motor rests. Later it measures 8 degrees, and the motor starts again. The sensor keeps the fridge cool without wasting electricity.
Look at the chart: electricity use is 3 in the morning and 9 in the afternoon. The afternoon uses 6 more units (9 − 3 = 6) because air conditioners work hard in the heat.
Engineers in a new farm area read sensor data and see that one field gets too much water. They change the watering. The data helped them use water well.
Class activity
Sensor in the classroom. On paper draw your classroom and mark where you would put three sensors, for example a thermometer for temperature, a light sensor near the window, and a motion sensor near the door. For each, write what it measures and what a program could do (for example, switch off lights when nobody is in the room). Then write two sentences on how this could save electricity at school.
Practice
1
What does a sensor do?
It measures something and sends the information to a computer.
2
What does a thermostat measure?
The temperature.
3
Electricity use is 4 at night and 9 in the afternoon. How many more units in the afternoon?
5 more units (9 − 4 = 5).
4
Why is electricity use highest in a hot summer afternoon?
