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New stuff you need
DC motor
Plastic bottle
Straws
Wooden skewers
More cardboard

AT THE halfway point of your maker journey, it’s time to really get moving. The simplest way is with a motor, which converts electric power into spinning motion. That’s got some obvious appeal for applications such as wheels or fan blades, but motors pop up everywhere, from vacuum cleaners to computer hard drives.

Look for a motor with a voltage range that encompasses the voltage of your battery. Mine says 3V to 12V, for example. If your battery supplies higher voltage than the maximum, you risk damaging the motor. If it delivers less than the minimum, it may run poorly or not at all.

Motors work because electricity and magnetism are two sides of the same coin: where you have one, you usually get the other. When an electric current passes through a coil of wire in the centre of the motor it produces a magnetic field. This creates an attractive force between the coil and permanent magnets in the motor’s casing, causing motion.

See for yourself. Connect the motor’s two wires to the battery terminals, and the rod protruding from its middle will spin. Recall how LEDs only work when wired one way round? Motors aren’t so fussy. Reverse the wiring and the rod will spin the opposite way. You can control the speed by altering the power – add some resistors to your circuit to see this effect.

For a more satisfying demo, slice the top off a plastic bottle and make a small hole in the centre of its cap. Then, cut some petal shapes from the rest of the bottle and glue them so they extend from the curved part of the cut-off bit. What you have made should look like a propeller. Slip the cap onto the motor rod (while it’s not spinning, of course) and glue it in place. Now you have a mini fan.

Or make a propeller-powered buggy. Glue two drinking straws – not plastic, now! – along opposite edges of a rectangle of card. Slip a wooden barbecue skewer through each, leaving a bit sticking out of the ends. Cut four circles from some more card, then poke the skewers through their centres and glue them together. Attach your battery and propeller to the card platform and watch it go.

And there’s so much more you can make. How about a motorised duster? Just glue some cloth to the propeller blades. Or add legs rather than wheels to make an automatic pot stirrer. You could use it to amuse your pets by attaching string to the motor and have it wind in when you press a button. Finally, what about a bath foamer: position the motor so that long spokes off its shaft disturb the flow from a tap and create more bubbles (beware: electricity and water don’t mix!).

To download a printable version of this page click here

Thanks to Imperial College Advanced Hackspace for use of their facilities

What you will need next week

3V battery

BBC micro: bit starter kit

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Next in the series

1 ÌýIntroduction

2 ÌýElectric candle

3 ÌýToast notifier

4 ÌýDesktop traffic light

5 ÌýPropeller car

6 ÌýMagic eight ball:ÌýBasic coding gives your device a brain

7 ÌýTheremin

8 ÌýSound-sensitive disco ball

9 ÌýRubbish sweeper

10 ÌýBiscuit bot

Projects so far and a full list of required kit are at
Email: maker@newscientist.com