Circuits & Control
Science FactA circuit is a complete loop that electricity travels around. Every robot brain, sensor and motor is wired into circuits.
A closed loop
Electricity only flows when there's a complete path from the battery, through the parts, and back again. A switch works by opening (breaking) or closing that loop. If any wire comes loose, the whole circuit stops.
Series and parallel
In a series circuit, parts sit one after another, so the same current goes through all of them; if one breaks, everything stops. In a parallel circuit, each part has its own path, so one can fail while others keep working. Your home's lights are wired in parallel.
Resistance and Ohm's law
Resistance is how much a part resists current, measured in ohms. Ohm's law says voltage = current × resistance. Engineers use resistors to protect small parts like LEDs from getting too much current.
Logic: how a robot brain decides
Microcontrollers are packed with billions of tiny switches called transistors. They turn on and off to represent 1s and 0s. By combining them into logic like AND, OR and NOT, a chip can run a program such as 'IF obstacle AND moving forward, THEN stop'.
- Battery (+)
- Switch
- Resistor
- LED
- Back to battery (−)
COOL REAL FACTS
- A modern phone chip has over 15 billion transistors.
- The first transistor was built in 1947 at Bell Labs.
- Arduino microcontrollers are used by students all over the world to build robots.
SCIENCE FACT vs SCI-FI
A Sentient Core that thinks and feels is fiction. Real robot brains are circuits running programs.
TRY IT (SAFELY!)
With an adult, build a simple circuit with a battery, an LED, a resistor and two wires. Add a paperclip as a switch and watch the loop open and close.
REAL ENGINEER TIP
Engineers draw a circuit diagram before connecting a single wire.
PARTS THAT USE THIS IDEA
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