⚡ Simple Electric Motor: Spin a Coil with Magnetism
Build your own working electric motor using recycled copper wire, a battery, and a magnet. Understand electromagnetism, commutator action, and how real motors power drones, EVs, and factory machines. Zero fancy tools — perfect for low-resource learners on the CBC journey.
🧲 Why build an electric motor?
Every spinning fan, washing machine drum, or electric car wheel uses the same principle: a coil of wire becomes an electromagnet, interacting with a permanent magnet to produce rotation. This project demystifies physics for CBC learners. You will create a “homopolar motor” variant — simple and mesmerizing. It shows how electrical energy becomes mechanical motion. Plus, you’ll learn troubleshooting skills used by real engineers.
📦 Zero-Cost / Recycled Materials
You will need (mostly from home or school lab):
- Enameled copper wire (magnet wire) – 50cm to 1 metre. Recycle from old broken headphone cables, small transformer, or ask a local electronics shop for offcuts. If not available, thin insulated wire works but strip ends carefully.
- One strong neodymium magnet (or 2-3 small ferrite magnets) – can be salvaged from old computer hard drive, old speaker magnet, or buy cheap at 20-50 KES.
- 1 × D-size or AA battery (1.5V). A new battery works best. You can also use a recycled power bank cell (3.7V is too high – use only 1.5V).
- Thick paperclip or stiff copper wire (to make supports). Two paperclips as stands (or use plastic straw + rubber band).
- Sandpaper or a small file – to remove enamel insulation from specific parts of the wire (critical for motor action).
- Rubber band or tape – to hold the battery and supports together.
- Cardboard or wooden base (optional). Recycled cardboard works.
Total cost: 0–100 KES (if you buy magnets and scavenge wire). Most items are from broken electronics or household junk.
🛠️ Step-by-Step Motor Construction
Follow these instructions carefully – the most important step is sanding the coil ends correctly.
Wind the coil
Take your enameled copper wire and wrap it around a cylindrical object like a AA battery or a marker pen (about 1.5–2cm diameter). Make 5 to 8 tight loops. Slide the coil off carefully; you'll have a small ring shape. Leave two long tails (each about 5–6 cm) extending from opposite sides of the coil. The tails will become the axle and electrical contacts.
Prepare the axles (the magic sanding step)
This is the most important part! Using sandpaper, remove the enamel insulation completely from the top half of each tail for about 1-2 cm length. But one tail: sand all around (full 360°). The other tail: sand only the top side (180°). This creates a simple commutator. The half-sanded tail ensures that current only flows when the coil is in the correct position, giving it a push each half-turn.
Make the support stands
Take two paperclips and straighten them partially, leaving a small loop at the top to cradle the coil’s wire tails. Bend them into an L-shape or U-shape to stand upright. Attach the stands to the battery using rubber bands or tape: one stand on the positive terminal (+), the other on the negative terminal (-). If you use cardboard base, poke stands through and connect wires to battery via alligator clips.
Place the magnet
Attach the neodymium magnet directly to the top or side of the battery, right beneath where the coil will sit. The magnet should be as close as possible to the coil (about 2-5mm clearance). If the magnet is weak, stack two or three magnets. The magnetic field must pass through the coil area.
Mount the coil and balance
Carefully rest the two sanded tails (the axle) into the loops of the paperclip stands. The coil should be positioned directly above the magnet, free to rotate without touching the magnet. Adjust the stands so the coil is level and spins easily. Give it a little flick — it should spin freely for a second without friction.
Start the motor – give it a push!
Connect the stands to battery (they already are). Gently spin the coil with your finger to start. If everything is correct, the coil will continue spinning! Try reversing the battery polarity or flipping the magnet to change speed/direction. If it doesn’t spin, check troubleshooting section below.
🐞 Troubleshooting (common problems for beginners)
- No spin at all: Check that both axle tails are touching the paperclip stands (good electrical contact). Also ensure the half-sanded tail is properly oriented: the insulated part should break current when coil is vertical. Try sanding more thoroughly.
- Coil spins weakly then stops: Magnet might be weak (use neodymium). Battery may be drained. Replace with fresh AA or D cell.
- Coil won’t start even with push: Verify that the coil is directly above the magnet, gap about 2-3 mm. Also ensure both stands connect to battery terminals without loose connection.
- Wire gets hot: That’s a short! Make sure bare copper from one tail does not touch the other bare section except through the paperclip stands; also ensure coil loops are not touching each other electrically.
📊 SBA Observation Log & Engineering Notebook
Record your design iterations, failures, and improvements. Engineers learn from failed spins!
| Trial # | Coil turns | Magnet type | Spin success? (Y/N) | Rotation speed (slow/med/fast) | Changes made |
|---|---|---|---|---|---|
| 1 | 6 | Small ferrite | ____ | ____ | ____ |
| 2 | 8 | Neodymium | ____ | ____ | ____ |
| 3 | 5 | Stacked magnets | ____ | ____ | ____ |
| 4 | 7 | Reversed battery | ____ | ____ | ____ |
📸 Capture photos or a short video clip of the motor running and include in your project portfolio (for KNEC evidence).
📋 KNEC SBA Rubric – Simple Electric Motor Project (20 marks)
| Criteria | Exceeds (5) | Meets (4) | Approaching (3) | Below (2-1) |
|---|---|---|---|---|
| Coil & commutator construction | Coil symmetrical, neat, 5+ turns. Sanding precise: one full, one half-sanded. Good electrical contact. | Coil functional but slightly uneven. Sanding correct but may need adjustment. | Coil shape poor, one or both sanding errors; motor barely spins. | No commutator action, coil not completing circuit. |
| Magnetic circuit & assembly | Magnet optimally placed, stable stand, coil spins freely. Battery contacts secure. | Magnet placement functional but may be weak; some stability issues. | Magnet too far; stands wobble; motor requires frequent pushes. | No magnet or incorrect placement, no rotation. |
| Understanding of electromagnetism | Student explains Fleming’s left-hand rule, commutator operation, and real-world motor applications. Diagram labelled with current and magnetic field direction. | Basic explanation of motor principle, identifies parts. | Limited explanation, cannot identify commutator role. | No scientific explanation. |
| Engineering process & documentation | Complete log with 3+ trials, includes photos/video, describes troubleshooting. Shows improvement. | Log with 2 trials, basic notes, motor works. | Minimal documentation, motor only works after excessive help. | No log, motor not functional. |
- Add a cardboard disc as a “rotor” and attach a small piece of paper as a fan blade.
- Measure how many paper clips your motor can lift (by attaching a string to the axle). Demonstrate mechanical work.
- Research and present on “Electric cars vs petrol cars – role of electric motors in Kenya’s future.” Connects to CBC career pathways (engineering, renewable energy).
🚀 Career Connections – From CBC to Real World
🔧 Where can this project take you?
Electrical Engineer Renewable Energy Technician EV Mechanic Robotics Specialist Physics TeacherBuilding a simple motor is the first step toward understanding how wind turbines, electric buses, and industrial machines work. In Kenya, the e-mobility sector is growing — engineers who understand electromagnetism design affordable electric tuk-tuks and solar water pumps. CBC vision: empower learners to solve local problems using science. Your spinning coil is proof you can become an innovator.
📸 Project Gallery – show off your motor!
📄 Save or Print for School
Show your teacher the rubric, log table, and motor video. Good luck with SBA!