GREAT
EXPLORATIONS - Moving air | Forming
images | Reflecting light | Electricity
and magnetism | Spinning things | Making
sense | Changing colours | Making
sounds and waves | Moving to and fro
| Thinking about shapes
This is an old set of proven ideas, for reference. My latest designs are
far better!
Electricity
and magnetism
Simple
circuit
TEXT:
Can you switch on the light?
Remember that an electric current can only
flow round a complete circuit.
The current has to flow from one end of each
battery, round, and back to the other end. A single break anywhere in
the circuit will stop it.
This is based on an earlier version I designed in 1989. It was the simplest
way I could think up to convey the concept of a complete electrical circuit,
while at the same time making it a collaborative experience. It is impossible
to switch on the light without asking somebody else to hold down the other
two switches for you. It is powered by a hidden mains transformer via
dummy batteries: a small deception that I felt was acceptable for the
sake of low maintenance needs. The 'switches' are simply flat metal strips
which spring apart after you press them together.
Generator
TEXT:
Turn the handle and switch on the
light.
The generator makes electricity, but only
when you complete the circuit.
Notice the extra drag when you switch the light
bulbs on. The energy that lights them has to come from somewhere. It comes
from you. It is harder work to supply enough energy to light two bulbs.
Here you see an obvious benefit of careful juxtaposition of exhibits.
There is a close link between this and the one described above. The circuit
and the switches look identical. The two lamps are connected in parallel,
each with its own metal-strip-switch. Concealed circuitry prevents over
enthusiastic human dynamos from burning out the lamps.
Turning
magnets
TEXT:
Turn one of the magnets and see
what happens to the other one.
Do the ends of the two magnets always pull
together? Can you find a way to make the two magnets push apart?
The "north" and "south"
poles of each magnet are different colours. Two poles of the same kind
will repel, but a "north" and a "south" pole will
attract each other.
Static
dancers
TEXT:
Rub the top of the plastic dome
and see what happens.
After rubbing the top, try just pointing
your finger at the dancing objects.
Rubbing the clear plastic generates a charge
of static electricity. The small objects are first attracted, then repelled
after they pick up a similar charge.
The 'dancing confetti' is attractively backlit, also minimising the humidity
which sometimes stops electrostatic exhibits from working. This one works
well.
Hovering
magnets
(Sorry, no picture.)
TEXT:
Which of these magnets are not
pulling together?
Look closely at the way the colours are arranged.
The "north" and "south"
ends of each magnet are shown by different colours. Two "north"
poles or two "south" poles in any pair of magnets will push
each other apart.
Two sets of ceramic ring magnets, each sliding freely on a vertical bar.
Some pairs are attracting each other; others are repelling so that the
upper one hovvers intriguingly.
Magnetic
fluid
(Sorry, no picture.)
Move the magnet underneath the
tray of oily liquid.
What happens to the surface of the liquid?
What do you think might be mixed with oil to
make it behave like this?
I designed most of these exhibits, but not this one, supplied by Experimentarium,
Copenhagen, Denmark. This was one of the very few 'bought-in' exhibits
that passed my stringent criteria for robustness and low maintenance combined
with "child-appeal". It is attractively designed and strongly
made, with red plastic-covered magnets underneath a clear acrylic dome
containing the oil/iron-powder mixture.
GREAT
EXPLORATIONS - Moving air | Forming
images | Reflecting light | Electricity
and magnetism | Spinning things | Making
sense | Changing colours | Making
sounds and waves | Moving to and fro
| Thinking about shapes
This is an old set of proven ideas, for reference. My latest designs are
far better!
|
