16
17
18
19
16. Next, attach the “headlights”: Mount two medium gear wheels (7)
on the shaft plugs.
17. Now mount this small frame at the front of the model. The end with
the red anchor pins goes on top.
18. Now attach the cables to the engine. The red cable (21) attaches to
the positive pole, the black one (20) to the negative pole.
19. When you attach them to the battery holder, make sure that the red
one goes to the positive side and the black one goes to the negative
side.
Under the Artificial Sun
In the next experiments, we will find out how strong
your engine is, and what kind of performance your
solar module can deliver.
Experiment 11
>
You will need: your model, artificial Sun, smooth,
flat surface such as a table top
Instructions
Now place your tractor on a smooth, flat surface,
such as the top of a desk. Hold an artificial Sun
— e.g., a desk lamp — directly over the solar module.
Watch what the vehicle does.
Results
As soon as enough light strikes the solar module,
your tractor starts moving. When the tractor moves
beyond the cone of light, it stops: The solar module
isn’t getting enough light anymore.
Driving in Reverse
If you attached the cables correctly, your vehicle
moved forward. Now we’ll make it go backward.
Experiment 12
>
You will need: your model, artificial Sun, smooth,
flat surface
Instructions
Remove the solar module from the battery holder
and mount it the other way around, as shown in the
pictures on the left half of page 12. Place the vehicle
under the artificial Sun and let it move.
Results
When you turn the solar module, the direction of the
flow of current is reversed as well. So now the tractor
drives backward.
Experiment 13
>
You will need: your model, artificial Sun, smooth,
flat surface
Instructions
Now switch the cables at the battery holder or the
engine. What happens?
Results
Your tractor drives forward again. When the cables
were switched, the direction of current flow was
reversed yet again.
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