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Pocket motor

 
 

Overview

Materials needed, per student

  • 400 mm copper wire
  • 1 AA battery
  • 2 rare-earth (e.g. neodymium) magnets, approx 10 mm x 5 mm
  • 1 copy of the wire template

Practicalities

We think that this is the simplest electric motor possible. It does wear the battery out quite quickly, so use fresh batteries every time for best results. Also, be aware that the wire can get hot quite quickly, so handle with care.

If you use insulated or enamelled wire, make sure you strip the outer coating where the wire touches the battery and magnet with wire strippers or coarse sandpaper.

When using the wire template, it helps to fold the wire in half to make the centre point first. This means that an equal amount is left for each side, which will help the wire spin in a more balanced way.

Rare-earth magnets are very strong. You can buy them from educational suppliers, e.g. www.mutr.co.uk. Be careful when bringing two rare-earth magnets together in case your skin is trapped between them.

Discussion

  • What happens if you put the magnet on the other end of the battery? Why is that?
  • Can you make the wire spin in the opposite direction?
  • What happens if you use your finger to spin the wire in the opposite direction?

Extensions

  • Can you adapt the very simple motor design to make it more effective?
  • Look at more complicated motor designs online or in text books. How are they similar? How do they differ?
  • Can you make the motor do some work for you?
  • Can you make it go faster or slower?
  • Can you change the rotary motion into linear motion?

Links to everyday life

Ford UK designed the Comuta as a non-polluting car back in the 1960s. It was powered by four 12-volt lead batteries, and could reach a maximum speed of 37 mph (60 km/h). Modern electric cars, such as the Tesla Roadster, are able to accelerate from 0 to 60 mph (100 km/h) in about 4 seconds, and can reach a top speed of over 130 mph (210 km/h).

Many toys convert electrical energy stored in batteries into movement, sound, light and sometimes (as a by-product) heat.