A switch with no moving parts

Ask while they play

Both boxes switched the light on. Which one moved? What was different inside?

Spot it at home

• Streetlights and porch lights that come on by themselves at night: a light sensor sends the signal.
• Phones, tablets, TVs and game controllers: each is full of tiny transistors switching on and off very fast.
• A touch lamp that turns on with one light touch and nothing moving.

What could tell this switch to turn on, instead of a button?

How it helps a robot

• The robot's brain board is full of transistors. They are how it thinks in on and off.
• A transistor lets the brain switch a motor or light fast and quietly, with nothing to wear out.
• Fast on-off switching sets a motor's speed, so the robot can go slow or fast.

Talk about it later

Could a robot's brain press this button for us?