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Unit 10: Electricity Page 16
a conductor of electricity when (electrons) can race around the
dissolved in a solvent (like water). track at top speed. When you turn
the switch to the OFF position, it’s
This type of conductor is called an like a bridge collapse for the train –
‘ionic conductor’ because once the there’s no way for the electrons to
salt is in the water, it helps along jump across without the track.
the flow of electrons from one clip When you switch it to the ON
lead terminal to the other so that position (both sides), you’ve rebuilt
there is a continuous flow of the bridges for the train
electricity. (electrons).
In this case we’re using water as a When electric current passes
holder for different substances, like through a material, it does so by
salt. But you can use orange juice, electrical conduction, but there are
lemon juice, vinegar, baking different kinds of conduction, such
powder, baking soda, spices, as metallic conduction (metals)
cornstarch, flour, oil, soap, and electrolysis (where charged
shampoo, and anything else you atoms (called ions) flow through
have around. liquids).
Electrical Switches & Why does metal conduct
Burglar Alarms electricity?
Burglar alarms not only protect Metals are conductors not because
your stuff, they put the intruder electricity passes through them,
into a panic while they attempt to but because they contain electrons
disarm the triggered noisemaker. that can move. Think of the metal
Our burglar alarms are clever wire like a hose full of water. The
switches which use cool tricks in water can move through the hose.
electrical conductivity. I’ll also An insulator would be like a hose
show you how to turn these full of cement - no charge can
burglar alarms into sensors for move through it. Paper, rubber,
your robots. But first, let’s recap a and plastics make great insulators,
bit about electrical charge and because sometimes you don’t want
conduction. electricity to flow unless you say
so. And that’s exactly how we’re
Think of this switch like a train
going to make our burglar alarms.
track. When you throw the
switches one way, the train
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