Build yours at home · Build 001
Make the needle move
What we're doing
Make electricity with a magnet. Moving a magnet in and out of a coil of wire pushes electricity round the wire, and a meter shows it.
Biggest jump: +0 mV
About 20 minutes.
Goes with these lessons
Extra experiment: not in a lesson yet. Needs a multimeter.
Get these parts
- A strong magnet (hardware store)
- A small spool of thin insulated wire, about 16 feet (5 meters) (hardware or electronics shop)
- A multimeter with clip-on probes (hardware or electronics store)
- A cardboard tube or thick marker to wind on (household)
Keep it safe
Strong magnets pinch fingers and are dangerous if swallowed. Keep them away from small children, phones and bank cards.
Steps
- 1
Wind 50 turns of wire round the tube. Leave both ends free, then slide the coil off.
- 2
A grown-up strips a thumb's width of plastic off each end.
- 3
Set the meter to its smallest DC volts setting. Clip one wire end to each probe.
- 4
Push the magnet into the coil fast. The number jumps. Pull it out: it jumps the other way.
- 5
Hold the magnet still inside the coil. The number goes back to 0. Only a moving magnet makes electricity.
- 6
Put the magnet away from phones and cards.
Talk while you build
- What does the needle do while the magnet moves?
- What happens when you hold the magnet still?
More for grown-ups · printed parts
Optional equipment
Prints that make the build easier. None are required. Every build works with tape and clips.
Printables
A printed frame for winding a neat, countable coil. Leave the bolt out and pass the magnet through the middle.
Not printed yet
Grown-up references
Make: Electronics — Learning by Discovery · Charles Platt The grown-ups' guide. It has you try the experiment first and explains it afterwards.