Switches and Everyday conductors

Week 5:

We recapped what we knew about electricity flowing around a circuit in a loop, to e.g. light a bulb, and how if the circuit is broken then the bulb won't light.

We talked about how we might want to break a circuit on purpose, because otherwise the electrical thing, e.g. bulb, would be on all the time which is both wasteful and useless for all the time you don't need it! So what can we put in our circuit to break/complete it when we need to? A switch!

Our little circuit set came with a switch, which we looked at in a little more detail. It has a 0 and a 1 on it - why? 0 to mean it's off and 1 to mean it's on (useful to know in relation to binary code too!). An easy way to remember which number means what is that 0 means no power so off.

So how does a switch work? I had the girls build a simple series circuit from scratch each, independently, containing one cell, a bulb and a switch.

Then I asked them if we could use something else as a switch instead - what could we make a switch out from? What does it need to have? Two conductors which can break apart and touch together and an insulator around them so we don't get a shock when we touch it!

What could we use as an insulator? A piece of card folded in half maybe. What about as the conductor? M said we needed something metal, so what was there in the house which was metal?

Our making a switch investigation turned into a testing for conductors instead. 😂

They used the circuit with a single bulb they had made earlier and took out the switch, then they held one free wire each and touched the ends to the object they were testing. If the bulb lit up then it meant the object was an electrical conductor!

The objects they tested were: a £2 coin, a £1 coin, a key, the spine of a ringbinder, scissors (the blades and the handle), paper, a hair clip and a hair slide.

They came to the conclusion that all the metal things were conductors and all the non-metals were not! The metal hairclip didn't conduct electricity though... Why? Maybe because it was painted pink so the paint was an insulator? When they tried with a plain metal hairclip, they saw that the bulb did light up. 👍