Science -- Your Future, Scotland's Future
SCI-FUN Roadshow Exhibits -- Power Bike
SCI-FUN Roadshow Exhibits -- Power Bike
In this exhibit you learn about generating power through movement.

Most of the electricity in the UK is generated from movement. To do this we need magnets.

When we generate electricity in power stations we turn a wheel. This can be done by producing steam (see the Steam Engine exhibit to see how steam can create movement), from moving water or from moving wind.

Coils of wire are wrapped around a magnet, and the wheel is used to rotate either the wire or the magnet. Rotating a magnet with respect to a wire causes electricty to occur in the wire.

This what occurs in power station generators, but it also occurs in other kinds of generator too. When cars burn petrol, they use some of the movement energy created to move the car, and some of it to generate electricity for their lights, to charge up their battery, for their power-assisted steering and for any internal devices. Sometimes in remote locations, such as some campsites, where there are no electricity lines, we can use a petrol powered generator.

We can also generate electricity using our own movement. Small hand-powered generators are used in wind-up torches, radios and phone chargers, which charge up a battery. Some bicycle lights use a generator too, using the rotation of your wheels to power them as you cycle along.

Human power cannot be used to generate lots of electricity though. You see on the Power Bike exhibit how hard it is to generate enough power for electrical appliances, and you only cycle for a few seconds. Many electrical appliances need to be powered for hours at a time, so human movement would not be able to sustain power for long enough.

1 Most electricity is generated from ________.
2 How would you use wire and magnets to generate electricity?
3 What can we use in generators in remote locations?
4 What might you use a small hand-powered generator for?
5 Why is human power not suitable for powering most electrical appliances?
6 Do you know how hydroelectric power stations work?

1 Magnets can make electricity, and electricity can make magnets. Wrap some thin electric wire, such as a speaker cable, as many times as you can around a piece of steel or iron (such as cutlery or a large nail). Before this, make sure that it is steel or iron by seeing if a magnet will attach to it. Switch on the device, so that electricity is running through the wire. Now try to pick up some small items, such as paper-clips, with the wire-wrapped metal.
2 How much power do wind-up devices need? Get a wind-up torch/radio/phone charger and allow the battery to run completely down. Now wind it up at a continuous speed for 10 seconds. Switch it on, and time how long it takes to run down again. Wind it up for 20 s, 30 s, 40 s, 50 s and a minute, each time, timing how long it takes to run down. Make a graph comparing winding-up time to power time. Does it plateau off? What do you think the best winding-up time would be?