What is an electric circuit?

Electricity flows from the battery, through the motor, and back. Batteries push electricity round a loop called a circuit. The wire has paths going out and coming back. When the loop is complete, the motor spins; switch it off and the loop is broken.

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Try it yourself

Switch the battery box on and off. Watch the motor start and stop.

Build it: 14 builds that teach electric circuits

  • 🔋 Motor Buggy: Your first car that drives by itself — with a forwards/backwards switch and headlights! (level 3 of 5, about 30 minutes, 20 steps)
  • 📡 Spinning Radar: A motor-driven radar dish that sweeps round and round on a turntable — with a blinking light. (level 3 of 5, about 25 minutes, 15 steps)
  • 🪢 Belt-Drive Buggy: No gears touching: a loop carries the power from the motor down to the wheels. (level 3 of 5, about 35 minutes, 11 steps)
  • ⚙️ Clutch-Gear 2-Speed Car: Push the gear lever and a driving ring grabs a different gear: 1st climbs, 2nd races! (level 3 of 5, about 45 minutes, 18 steps)
  • 🔥 Twin-Piston Engine: See inside a car engine: two pistons race up and down in turns! (level 3 of 5, about 40 minutes, 22 steps)
  • 🌬️ Oscillating Fan: A desk fan that turns its head left and right all by itself! (level 3 of 5, about 40 minutes, 18 steps)
  • 🛢️ Nodding-Donkey Pump Jack: A slow crank rocks a long beam up and down — nod, nod, nod, all day long. (level 3 of 5, about 45 minutes, 30 steps)
  • 🎡 Ferris Wheel: A big wheel turns slowly while its gondolas always hang the right way up. (level 3 of 5, about 45 minutes, 28 steps)
  • 🦾 XL Power Crane: The strongest motor plus a worm gear: 24 times slower and super strong. (level 4 of 5, about 35 minutes, 27 steps)
  • 📦 Conveyor Belt: A factory belt that carries your parts from one end to the other — and drops them in a box. (level 3 of 5, about 50 minutes, 22 steps)
  • 🚂 Floor Express: A remote-control locomotive with headlights, a chimney and a log wagon. (level 4 of 5, about 40 minutes, 17 steps)
  • ↩️ Reverse-Gear Truck: The motor only spins one way — the gear lever decides forwards or backwards! (level 4 of 5, about 55 minutes, 18 steps)
  • 🏆 RC Racer: A real remote-control car: motor drive, differential, servo steering and headlights. (level 5 of 5, about 75 minutes, 38 steps)
  • 🕷️ Klann Walking Spider: A robot that WALKS instead of rolling — beams and pins turn a spinning crank into steps. (level 4 of 5, about 60 minutes, 17 steps)

In the classroom

Common engineering questions

How can I try electric circuits at home?

Switch the battery box on and off. Watch the motor start and stop.

Which builds teach electric circuits?

14 MightyCog builds teach it: Motor Buggy, Spinning Radar, Belt-Drive Buggy, Clutch-Gear 2-Speed Car and Twin-Piston Engine and more. Start with Motor Buggy: 20 steps, about 30 minutes.

Ideas that go with it