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Inside the Machine G3 to G5 / Week 02 / Wednesday
3/6
Week 02 · Input and output

Wednesday

Sensors feel the world
// Devices that take information in and send it out
⏱ about 15 min

Wednesday: Sensors feel the world

Rocket holds a tablet in the sunny doorway. "It got brighter all by itself!" he says. He walks into the shadows. The screen dims.

Raven tilts the tablet sideways. The picture turns to match. "What do you notice?" she asks. "Nobody touched a button."

Nova circles the tablet, lights flickering. "Some inputs do not wait for a tap," she says. "They measure the world around them. Would you like a hint? Feel for the sun."

Inputs that measure

A sensor is an input device that measures something in the world. It sends a number to the computer many times a second.

A light sensor measures how bright the room is. The tablet uses that number to set the screen brightness.

A motion sensor feels tilting and shaking. The tablet uses it to turn the picture when you turn the device.

A temperature sensor measures heat. A processor uses one to notice when it gets too hot.

SensorWhat it measuresWhat the computer does with it
Light sensorBrightness of the roomDims or brightens the screen
Motion sensorTilt and shakingTurns the picture, counts steps
Temperature sensorHeatSlows down or warns when too warm
Touch sensorWhere a finger isOpens what you tapped
MicrophoneSoundHears a spoken command

A microphone and a camera are sensors too. They measure sound and light. Every sensor follows the same path: measure, send a number, let the processor decide.

Sensor measures the room: dark
Processor decides: make the screen dimmer
Output: the screen dims

Sensors in everyday things

Sensors are everywhere. Some satellites carry sensors that gather facts about Earth from space.

Some street lights have a light sensor that turns them on at dusk.

A step counter can use a motion sensor. The sensor notices each step you take.

WHICH SENSOR IS AT WORK?
  • Read the question.
  • Tap your answer.
The screen dims when you walk into a dark room. Which sensor?
The picture turns when you turn the tablet. Which sensor?
A phone slows down because it is getting too warm. Which sensor?
A speaker answers when you say a command. Which sensor heard you?
A sensor is what kind of device: input or output?
WHY THIS EXERCISEA sensor measures the world and sends the number in. That makes it an input device.
StatementTrue or false?
A sensor sends information into the computer.?
A light sensor measures sound.?
A step counter uses a motion sensor.?
A sensor decides on its own what the screen should do.?
WHY THIS EXERCISESensors measure and the processor decides. That split is how every smart device works.
PUT THE AUTO BRIGHTNESS PATH IN ORDER
  • ?The screen dims
  • ?The processor decides to dim the screen
  • ?The light sensor measures less light
  • ?The room gets dark
WHY THIS EXERCISESensor, then processor, then output. The same path as a key press, but nobody tapped anything.
An input device that measures the world is called a what?
Which sensor turns the picture when you tilt the tablet?
Which part decides what to do with the sensor's number?
Try it
With a grown-up, hold a tablet or phone near a window, then in shade.
Watch the screen. Does it change brightness on its own?
Turn the device sideways. Does the picture turn?
Safety first
Hold the device with both hands over a soft surface.
Do not cover the device or leave it in hot sun.
◈ LOOK INSIDE A SMOKE ALARM

A smoke alarm has a light sensor inside a dark chamber.

Press step 1, Clean air. Watch the yellow beam and the light sensor.

Then try the other steps. When does the chip sound the horn?

You found the inputs that feel the world! Tomorrow you will meet one device that does two jobs at once.

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